The Shire Hall Gallery and Shugborough Estate in Staffordshire have been cleared to join a bid to secure the recently discovered Anglo-Saxon Treasure, found by a metal detectorist in the county in July.

The two locations have been granted accreditation by the Museums, Libraries and Archives Council, and have joined Birmingham Museum and Art Gallery and Stoke's Potteries Museum and Art Gallery in a bid to buy the Staffordshire Hoard.

The 1,500 items, discovered in July by a metal detectorist, are being kept at the British Museum, with an initial valuation due on 25 November. They attracted 40,000 visitors in 19 days when displayed at the Birmingham museum. The Midlands museums have 13 months to raise the cash, although the deadline may be extended.

Simon Cane, Birmingham Museums and Art Gallery's head of operations, said a fundraising campaign had already begun.

"Whatever the valuation, we need to raise more to cover interpretation, research and conservation," he said. "It is going to be a seven-figure sum."

Cane said a home for the hoard was "to be agreed". Staffordshire County Council said it had the "capacity, capability and competence" to house the collection.

Billed as the most significant UK treasure discovery since 1939, the finds are being displayed at the British Museum this month.

But a spokeswoman said the exhibition was temporary and the museum would act as an acquirer of last resort only if the Midlands partnership could not raise the funds.