The debate over gallery entrance fees has been reignited after the National Galleryraised the cost of an exhibition ticket beyond £20 for the first time, charging £22 for its Claude Monet exhibition on weekends.

Gabriele Finaldi, the gallery’s director, this week admitted that Londonexhibitions “have become quite expensive” but blamed this on the cost of staging large-scale shows. “We couldn’t have put it on for free, because that’s not the way we operate,” he told BBC Radio 4’s Today programme on Friday. “There are other exhibitions we put on for free.”

Finaldi said the National had offered early bird tickets at reduced prices and argued the exhibition was worth the ticket cost.

    

“There’s a good number of paintings which have not been seen in public before,” he said. “Those are the pictures that are most difficult, sometimes impossible for the public to see. To have brought those in and to be able to show those in this exhibition I think is very attractive for the public.”

But Labour’s Tom Watson, the shadow culture minister, said that increases in museum costs were down to “huge cuts to arts budget over the last eight years”. Adding that the cost was prohibitive for some people, he said: “Galleries need to be careful to balance the need to raise funds with the key obligation to widen access to art to as many people as possible.”

Monet & Architecture will cost £20 on weekdays and £22 on weekends. But the National is not the first to charge more than £20 for tickets. Entry to Picasso 1932: Love, Fame, Tragedy at Tate Modern is £22 for adults, and last year the Victoria and Albert Museum charged £24 for Pink Floyd: Their Mortal Remains on weekends and £30 for its extended opening.

The Turner prize-winning artist Jeremy Deller said while the price might discourage young people from seeing certain exhibitions, income from shows such as this was needed to subsidise museums.

“Maintaining free entrance to museums’ collections is more important,” he said, as was “increasing the number of foundation course places for young people at art colleges”.

The Arts Council England budget has been cut by 30% since 2010. It said the long-term squeeze on public funding in the arts and cultural sector had resulted in some organisations it supported having to increase ticket prices.

“Whilst we do not set ticket pricing for organisations, it is a condition of Arts Council investment that organisations are able to continue to demonstrate how they will grow and broaden their audiences and increase access to the communities they serve,” a spokeswoman said on Friday.

General admission to the main sites of all the UK’s national museums has been free since 2001, and has helped make Britain’s museums and galleries some of the most visited in the world. But it means they rely on government funding or special exhibitions to survive.

Critics say this has created a two-tier system, whereby only tourists and higher spenders can afford the special exhibitions.

A report by the Department for Digital, Culture, Media and Sport in November found the nation spends around £844m of taxpayers’ money each year on about 2,600 public institutions, down more than £100m on a decade ago.

The Mendoza review declined to re-examine the UK’s policy of free entry or discuss the costs of special exhibitions in museums with free entry.