Last week (ends31Jul16) executives at the company, formerly known as British Petroleum, announced $9.92 million (£7.5 million) worth of sponsorship deals with U.K. arts organisations including the Royal Shakespeare Company (RSC), the British Museum and the National Portrait Gallery.

However in a letter published on Tuesday (2Aug16) in U.K. newspaper The Times, Mark and Ezra joined more than 200 arts figures, campaigners, and scientists in calling on the arts bosses to hand back the sponsorship money due to the company's alleged poor human rights record and the importance of fighting climate change.

"We believe museums, theatres and galleries are public institutions that must play a positive role in taking urgent climate action and defending human rights," the letter reads.

"If the world is to avoid rapid and devastating climate change in the coming decades, most of the oil on BP's books cannot be burned. Meanwhile some of the company's activities continue to harm lives every day despite community resistance from the Gulf Coast (of the U.S. and Mexico) to Australia."

The letter also alleges that BP's sponsorship funding comes with "strings attached" and that company executives had influenced the timing of exhibitions and curatorial decisions.

It concludes, "BP is not welcome to use our culture to promote its destructive business - these deals must be cancelled."

The new letter is not the first time Mark, who won the Best Supporting Actor Oscar earlier this year (16), has campaigned for BP to be dropped as a provider of arts funding.

In March (16) he joined the actress Emma Thompson, fashion mogul Vivienne Westwood and Bianca Jagger in urging the director of the British Museum to tear up a previous sponsorship agreement.