BP is to end its 26-year sponsorship of the Tate next year.

The oil firm blamed the “extremely challenging business environment” rather than years of protest against the sponsorship, the Independent reported.

Last summer protesters spent 25 hours scrawling climate change messages in charcoal on the floor of Tate Modern’s Turbine Hall. In November activists occupied part of Tate Britain, where they started to tattoo each other with the numbers of the CO 2 concentrations in the atmosphere in the year they were born.

The art collective Liberate Tate, which staged the protests, said thousands of people had called on Tate to end its contract with BP on ethical grounds.

Group member Yasmin De Silva said: “We’re thrilled with the news Tate is rid of BP. About 30 years ago, the tide turned on tobacco sponsorship, and now the same thing is happening to the oil industry. Of course Tate won’t rub it in BP’s face by acknowledging this decision is the result of the increasing public concern about climate change and the huge number of artists, members and gallery-goers speaking out against the controversial deal.”

Tate figures released last year, after a three-year legal battle, showed for the first time how much money BP had paid Tate over a 17-year period. The total was £3.8m, given in annual amounts varying between £150,000 and £330,000 – an average of £224,000 a year.

The revelation, which came after Tate lost a case at a freedom of information tribunal, put into the spotlight BP’s sponsorship of arts institutions, including the Royal Opera House, the British Museum, the National Portrait Gallery and the Royal Shakespeare Company.

A Tate spokeswoman told the Independent the sponsorship had been an “outstanding example of patronage and collaboration over nearly 30 years”. She said the company’s support “represents one of the most significant long-term corporate investments in UK arts and culture”, and expressed gratitude to BP for its “groundbreaking support of the collection displays and other programmes”.

A BP spokeswoman said the decision to end the sponsorship was unrelated to any pressure from activists. “They are free to express their points of view but our decision wasn’t influenced by that. It was a business decision,” she said, adding that were no plans to end sponsorship of other arts institutions.

Peter Mather, head of BP in the UK, said: “The decision to end our contractual relationship with the Tate has been a very difficult one. It reflects the extremely challenging business environment in which we are operating.

“We have seen the Tate’s extraordinary growth and success and we are proud to have played a small part in that.”

BP last renewed its sponsorship of Tate and other institutions in 2011. Tate director Nicholas Serota said at the time that his organisation had thought very hard about the sponsorship, and the board had “decided it was the right thing to do to continue with BP, who have been great supporters of the arts”.

The culture minister, Ed Vaizey, welcomed “BP’s renewed commitment to four of Britain’s great cultural institutions”.