Greenpeace activists have temporarily closed the British Museum in protest at an exhibition sponsored by oil giant BP. More than a dozen activists scaled the famous columns outside the museum in central London in a bid for it to end the partnership with BP for its new Egypt display, Sunken Cities.

The environmental campaigners are placing banners on the columns with images of places that "evoke flooding, extreme weather and rising sea levels", including New Orleans – which was left devastated following Hurricane Katrina in 2005 – and areas of the UK that have been seriously affected by flooding.

The BP-sponsored Sunken Cities exhibition features items recovered from the lost ancient Egyptian cities of Thonis-Heracleion and Canopus.

A Greenpeace spokesperson said: "The British Museum dedicates itself to learning, discovery and the conservation of human cultures, but the only discoveries BP seeks are more fossil fuels to dig up and burn, which are already polluting our air and warming our world. We're here today taking a stand because of the irony of an oil company sponsoring an exhibition whose name practically spells out impacts of climate change

"Sunken cities aren't a thing of the past, they are happening now. And if BP gets its way, they could come to define our future. We think every visitor passing through the famous columns today, and anyone who wants to imagine a culture beyond oil, deserves a say in whether it's OK for a company whose business contributes to climate change to make it past the bag checks."

A British Museum spokesperson said: "The museum is closed temporarily for visitor safety reasons. We hope we will be able to reopen shortly."

A BP spokesperson added: "BP has a long history as a major supporter of arts and culture in the UK and we are proud to have partnered the British Museum for 20 years, supporting significant exhibitions such as the new Sunken Cities exhibition."

Greenpeace protesters attempting to unfurl banners down the British Museum columns Greenpeace