Around 250 staff at the National Gallery in London started the first of five days' worth of planned strike action this morning over plans to outsource hundreds of jobs to a security consultant who used to work for G4S.

Staff walked out after the breakdown of discussions between management and unions over the gallery’s planned privatisation. The Public and Commercial Services Union said that one of its senior reps had been suspended as a result of the dispute.

According to British activist group 38 Degrees, the National Gallery’s board of trustees have announced they have no choice but to press ahead with plans to outsource more than 400 jobs to a temporary security consultant, who reportedly used to work with G4S.

The jobs likely to be privatised include: “those who look after paintings, deal with the public and requests for information about the collections”.

Mark Serwotka, general secretary of the Public and Commercial Services Union (PCS), said: "This dispute and the sell-off plan are putting the global reputation of the National Gallery at risk.

"Suspending one of our senior reps on the eve of our strike is a disproportionate act of unfathomable bad faith and not only should she be reinstated immediately, the gallery must commit itself to full and proper negotiations."

A PCS-initiated petition against the privatisation plans has garnered over 38,000 signatories in the last six months and will reportedly be delivered by union members to the gallery board of trustees during the strike action.

The petition has been officially supported by a number of other organisations, including the Peoples' Assembly, the Musicians' Union, Lost Arts, BECTU and SERTUC.

A spokesman from the National Gallery said: "The National Gallery is a public asset and we have a duty to ensure the collection and the Gallery itself is accessible as much as possible, to as many people as possible.

"However in order to allow these plans to be implemented we need to introduce a new roster for some visitor-facing and security staff to enable the National Gallery to operate more flexibly.

"The PCS union leadership oppose these changes and, despite months of dialogue, we have not been able to reach any agreement with them. During these discussions, we proposed not only to meet the London Living Wage, but also to pay a basic salary in excess of it.

"As a result, the National Gallery will now appoint an external partner to manage these services. There will be no job cuts and terms and conditions will be protected."

According to the National Gallery 132 employees (60.8 per cent of PCS members) voted in the strike ballot. The gallery claims that those numbers represent just 22 per cent of its overall workforce.