How should we be using the internet to involve the public with museums and to meet the needs of professionals? Museums think they have the answer; the government thinks it has the answer. But there seems to be a widening gulf between what the sector is seeking and what those holding the purse strings are providing.

In the red corner are the digitisers, a hard-core of curators and academics who dream of being able to peruse data from any collection in the world at the click of a mouse. In the blue corner are policy-makers, who see the web not as a potentially all-embracing archive, but primarily as a tool for reaching out to those who haven't traditionally engaged with museums.

Back in the heyday of New Labour, there was a broad consensus that digital culture should be used to promote social inclusion. But alongside this came the tantalising promise of a holy grail for many working in the sector: a fully integrated online portal providing links to information on all the key treasures in our museums.

For a time, this was where everyone seemed to be heading. In 1999, the New Opportunities Fund (since renamed the Big Lottery Fund after being merged with the Community Fund) launched nof-digitise, a £50m programme designed to provide an online gateway linking schools and libraries to Britain's key collections.

The resulting website, EnrichUK, contained details on 30,000 objects held in 150 museums. Then came Cornucopia, a database set up by Resource, now the Museums, Libraries and Archives Council (MLA), to provide curators with a comprehensive A-Z of the holdings of some 6,000 collections across Britain.

Soon individual museums were at it too. The Tate began assembling a mammoth digital collection that has grown to include 65,000 items and is now known as its fifth gallery. The British Museum is in the middle of an ongoing drive to scan some 300,000 images and write text entries for a further 1.5 million artefacts.

But somewhere along the line, any overarching strategy behind this once trumpeted digital cultural revolution appears to have lost its way. Barely three years after its launch, EnrichUK is defunct. Alongside Cornucopia, it is to be absorbed into one all singing, all dancing Knowledge Web by the MLA - but a timetable has yet to be announced.

Every Object Tells a Story, a collaboration between the Victoria and Albert Museum and Channel 4 that invites public and professionals to contribute to an online archive of stories about objects they value, currently contains entries from a mere seven museums.

And Culture Online, the umbrella organisation set up in 2002 by the Department for Culture, Media and Sport (DCMS) to promote cultural engagement through new technology, closes down this year. It will leave behind a patchwork webscape of 16 sites - most of which, however imaginative, focus almost entirely on interactivity, while containing little in terms of digitised 'stuff' to interact with.

At the mercy of this spaghetti junction of websites are hundreds of frustrated curators and a baffled public that neither knows where to turn for information nor (if user rates are anything to go by) feels engaged by much of what's on offer. In 2004, the DCMS's UK World Heritage Sites portal recorded a mere 77 unique visitors - the lowest annual tally to date for any site launched by the department. Granted, it only went online in November that year, but three months into its life, in February 2005, it attracted just ten visitors - a feat it repeated in April that year. The monthly tally for the Tate is more than a million.

So how has the pursuit of this brave new virtual world veered off course? Mike Greenwood, the commissioning executive for Culture Online, insists his end of it hasn't. 'Our overall brief was to engage audiences in culture through new technology. There was a slight weighting towards harder-to-reach audiences - ones that are digitally excluded, particularly from ethnic communities, or technology avoiders like the elderly. On the whole, I think we've been very successful.'

Certainly, some Culture Online sites have impressive user rates. In its first seven months, Icons - the site dedicated to enduring emblems of British culture - attracted three times its first year target of 150,000 visitors. Similarly popular is Plant Cultures, an educational site devoted to South Asian flora, now maintained by the Royal Botanic Gardens, Kew.

Visitors to these sites - often whole school classes - use them qualitatively too, by joining online activities. 'It's worth paying more money to get people to contribute to a site, rather than passively consuming,' Greenwood says.

But not all this money - £4.2m-plus since Culture Online's launch - has arguably been so well spent. The Dark, an ambitious site with a finite lifespan designed to bring alive the 18th-century slave trade using ghostly graphics and stories drawn from real-life experiences, required such high-spec software to navigate it that many PCs will have crashed in the attempt.

Keith Nichol, the head of museum education at the DCMS, concedes that not all such experiments have been successful, but argues that the government is right to use a certain amount of taxpayers' money to explore ways in which socially excluded groups might be engaged with museums, as the Dark tried to. 'If there's market failure, it's at times right for the public sector to invest,' Nichol says.

His view is echoed by Ross Parry, a museum studies lecturer at the University of Leicester, who says museums should use the web to redefine themselves as receivers as well as givers of information.

The advent of blogs, chat-rooms and Wikipedia-style 'open source' sites to which anyone can add their personal views should, he argues, be embraced as a way of both reaching out to the marginalised and enhancing museums' own research by inviting input from source communities with hands-on experience of objects in their collections. The test will be whether museums are willing to accept the interpretations of people other than their own experts as equally valid.

'If a 14-year-old looks at an axe-head and says it's "minging", isn't it wonderful they have a right to say that?' Parry says. 'We don't want an intellectual apartheid between those in the know and those who have a visceral response to things.'

Not everyone agrees. David Jillings, the head of new media at the British Museum, says: 'Are the public more interested in "our" view or "your" view? While there's evidence that personalisation is good as an educational tool, it's not clear the public want to read what Jenny in form three thinks about something.'

Jillings argues that museums should view their sites as a means of both attracting more visitors and displaying their collections to geographically remote communities who are unlikely to ever be able to visit them.

Maurice Davies, the deputy director of the Museums Association, says it comes back to the question of overall direction. 'One unresolved inconsistency is that there's a big group of people in museums who would like to get all their collections online, but the other drive - in many ways at odds with this - is to reach ordinary people through interactivity.

'There isn't any sense of a common strategy,' Davies continues. 'The greatest disappointment is that the MLA was set up to sort out this whole online digitisation issue.'

The MLA insists it is doing this. Its head of digital futures, David Dawson, says its long-awaited Knowledge Web will be a single, user-friendly portal accessed via a 'souped-up version' of the 24-Hour Museum - the DCMS-funded site that attracts half a million visitors a month. Tenders will go out soon, and the new site should be online early next year. 'In terms of leadership, we have spent upwards of £15m on digitisation projects in the past three years,' Dawson adds.

But some would argue it's not a question of how much has been spent, but what it has been spent on.

'Ten years ago, websites were largely just databases, but things have moved on and people want to do different things on them now,' says Parry at Leicester. 'A museum today isn't just a building. It's a building and a website, and something you can have on your phone - or access by pressing the red button on your TV.'

James Morrison is a freelance journalist and lecturer