Sir Nicholas Serota is the director of the Tate

Sir Nicholas Serota said it was not necessarily better to buy pieces to display in the UK rather than abroad just because they were already here.

Speaking at an acquisitions conference, he suggested more should be spent on 20th Century and contemporary art.

The UK Government recently stepped in to prevent Raphael's Madonna of the Pinks being sold overseas.

Sir Nicholas pointed out that �60m had been handed out in 14 grants by the Heritage Lottery Fund to prevent items already in the UK from being sold abroad.

'Social chauvinism'

Joshua Reynolds' Portrait Of Omai was kept in the UK

"The belief that a work is always better seen in a British public collection than in a foreign public collection needs to be tested by reasoned argument rather than simple appeals to national or social chauvinism," Sir Nicholas told the conference organised by the National Art Collections Fund.

"It is not always self evident that acquisition by a public collection in the United Kingdom is necessarily a better solution than public exhibition abroad."

The Tate recently paid �12.5m to buy Joshua Reynolds' Portrait of Omai, following a donation from an anonymous benefactor.

It was thought to be going into an overseas collection before the government placed an export ban on it in the hope of finding a British buyer.

Look overseas

Sir Nicholas said museums should place the interests of the public above that of the institution, which were not always the same thing.

New forms of ownership may be needed in future where galleries in two or more countries share a work, he said.

There had been a failure to create major collections of international 20th century art since those made by Frank Stoop and Samuel Courtauld in the 1920s, he added.

"I do wonder whether, as a nation, we care too much about what happens to be here as a result of history," he said.