A demonstration has been held at the Scottish National Portrait Gallery by campaigners protesting against oil giant BP's sponsorship of a prestigious award.

An exhibition of the BP Portrait Award, an annual competition which showcases the best contemporary portrait painting from around the world, has been on display at the Edinburgh attraction since October.

It is organised by the National Portrait Gallery in London but goes on tour to different venues.

Artists and activists from the group BP or not BP held a "performance protest" at the gallery in the Scottish capital on Saturday as part of a demonstration against the sponsorship deal which has been in place for more than 20 years.

Members of the environmental protest group displayed banners and sang songs as well as delivering a letter to the director of the gallery and inviting members of the public to sign a petition.

Claire Robertson, a participant in the performance, said: "BP have sponsored the awards for 25 years as the evidence of climate change has become far clearer and the need to act ever more urgent.

"Fossil-fuel companies who are profiting from the destruction of the climate should not be allowed to paint themselves as respectable organisations with deals like this."

A spokesman for National Galleries of Scotland said: "The BP Portrait Award exhibition which finishes tomorrow has been enjoyed by many thousands of visitors during its run in Edinburgh.

"This afternoon there was a brief protest at the portrait gallery and we, of course, respect the right of people to air their views in a peaceful manner."

A spokesman for BP declined to comment.

Video by Stewart Attwood