Workers at Britain's National Gallery in central London walked out Saturday afternoon in an escalation of protest at plans to restructure jobs over big cuts in the gallery's budget.

Members of the Public and Commercial Services Union (PCSU) walked out of work at 4 p.m., one of the busiest times and on one of the busiest days of the week in the iconic cultural landmark on Trafalgar Square.

Large parts of the gallery were shut down, and visitors expressed their disappointment at being unable to see some of the famous paintings.

Gurt Roth, a 33-year-old visitor from Hamburg in Germany, told Xinhua he was very disappointed not to see any of the landscape paintings by 19th century British painter William Constable, whose most famous works -- such as "The Haywain" -- are at the core of the gallery's collection.

"I came to London with my girlfriend for the weekend, and it's very disappointing not to be able to see these paintings," said Roth.

Gallery staff said that rooms had been shut "because of industrial action," and nearly three quarters of the gallery's floor space was shut down.

The gallery is currently hosting a sold-out exhibition of Leonardo da Vinci drawings. Gallery staff said this exhibition was unaffected by strike action, and that the parts of the gallery that were open had been kept open to allow access to it from all the entrances to the gallery.

The PCSU said there would be a further strike on Thursday, Feb. 2, over plans to make gallery attendants guard two rooms at the same time, instead of just one.

The PCSU said the coalition government had axed 15 percent from the gallery's budget as part of plans announced by Cancellor of the Exchequer George Osborne to cut 81 billion pounds (about 127.4 billion U.S. dollars) from public spending up to 2015, in the face of near record government deficit of 127 billion pounds for 2011/12.

The PCSU, which represents 90 percent of the gallery's 200 gallery assistants, said the cut amounts to about 4 million pounds (6.3 million U.S. dollars) for the period up to 2014/15, 1.5 million pounds through staffing.

Last summer one of the gallery's most famous works, Nicolas Poussin's 'Adoration of the golden calf' was vandalized, and the PCSU said this was in a room without an assistant.

A spokeswoman for the gallery told Xinhua that this was not the case, and plans to change the gallery assistants' jobs had been mapped out before the gallery's budget cuts.

PCS General Secretary Mark Serwotka said: "As well as hosting high profile exhibitions like Da Vinci, the gallery is home to some incredibly valuable works of art, not just in monetary terms but in their contribution to culture and our society."

"But instead of investing in the arts and the people who look after them, the government has imposed massive spending cuts on our museums and galleries to pay for an economic crisis caused by bankers, and we are now seeing the impact of this on the National Gallery and elsewhere," he added.

The PCSU has close links with one of the largest unions in the public sector, Unite union, and a merger between the two has been proposed.

Unite is strongly opposed to the government's austerity budget cuts, which are costing the jobs of thousands of its members.

Unite, the PCSU and 25 other unions joined forces for a one-day strike at the end of November, the largest in Britain for 80 years.

Speaking on a picket line, Unite General Secretary Len McCluskey told Xinhua that if the government persisted with its plans and jobs continued to be axed then industrial action could continue "up to and during the Olympic Games" which start in London on July 27.