Strikes are to hit the National Museums of Scotland tomorrow and Friday after talks over weekend working pay and conditions failed.

The Public and Commercial Services union (PCS) confirmed that staff at the National Museum of Scotland (NMS) will walkout tomorrow afternoon and all day on Friday.

The strike is the latest action in a two year dispute over weekend pay and conditions.

The PCS has met with NMS management and Fiona Hyslop, the culture secretary, but talks have come to naught.

Lynn Henderson, PCS Scottish Secretary, said: "It was only a few weeks ago that the National Museum Scotland topped the poll as the most visited tourist attraction in Scotland, but they have come bottom of the league this week for poor industrial relations.

"Museum management and Scottish Ministers have proved to be intransigent throughout the process.

"It is interesting that Scottish Ministers approve £7m to pay a bonus to Prison Officers but turn a blind eye to the lowest paid workers being stripped of payments for weekend working.

"Our members are now forced to take strike action again and have indicated that their resolve remains strong."

PCS members will walk out of the National Museum in Chambers Street at 1.30pm tomorrow.

This will be followed by a rally outside the Scottish Parliament at 2.30pm.

A statement from the NMS said: "Like many other public sector organisations, National Museums Scotland has had to make a wide range of changes in order to manage the reduced budgets which have been a result of the financial crisis. "These changes have included reducing staff numbers, reducing a range of budgets, constraining some services and introducing a change to some terms and conditions for staff newly appointed to ensure that we could continue to operate within the funding available.

"National Museums Scotland supports public sector pay policy and delivers the Scottish Living Wage for all its employees.

"Over recent years, including the period when a public sector pay freeze was in place for the majority of staff, we have differentially increased pay levels for our lowest paid staff."

It adds: "Weekend payments are no longer common in the culture and tourism sector across the UK.

"In January 2011, National Museums Scotland introduced revised contracts for new staff who are employed to work weekends; these new contracts do not include weekend working allowances.

"We explicitly communicate the terms at key stages of recruitment and on appointment.

"No member of staff has received a pay cut following the introduction of new contracts. Existing terms and conditions have been preserved for all staff employed prior to 2011."