Most of Scotland's museums were affected by a 24-hour strike by about 150,000 council workers affiliated to the Unison, Unite and GMB unions in August.

All museums run by Culture and Sport Glasgow and Edinburgh City Council were forced to close. Another walkout was scheduled for
24 September, following the breakdown of negotiations between the unions and the Convention of Scottish Local Authorities.

So far, the only concession granted has been to limit the 2.5 per cent pay offer already made to one year instead of the next three. But unions have rejected the proposal.

Almost all Scottish local authorities employ museum staff, about two-thirds of whom are Unison members. However, national museums are Scottish government bodies and their staff belong to civil-service unions, which are not involved in the dispute.

Kelvingrove Art Gallery and Museum, which is run by Culture and Sport Glasgow, shut during the August strike, despite being a charitable trust. A spokesman said he hoped another closure could be avoided, as the museum was separated from council control in 2006.

"Our pay negotiations with our employees are separate and a matter for us," he said. "But the unions believe it is part of the same dispute - there is a conflicting viewpoint."

Unison members were due to vote on further action at its Scotland Local Government Conference in Glasgow last month. Unite and the GMB have pledged to follow suit.

Unite's regional official, Jimmy Farrelly, said: "Initially, the employers indicated that they would offer a one-year deal which would take the recent rises in inflation into account.

"However, they came back with a one-year deal of just 2.5 per cent, which is exactly the same as their previous offer."