The British Museum in London closed to visitors on Thursday after Greenpeace activists scaled its entryway columns in a protest against BP's sponsorship of the blockbuster exhibition "Sunken Cities: Egypt's Lost Worlds."

Police arrested about 11 people in the protest for aggravated trespass. The museum remained closed for four hours and said it would refund visitors with tickets to the exhibtion that day.

Greenpeace has repeatedly protested BP sponsorship of cultural institutions as a means for the oil company to "clean up its image" and "distract from the polluting reality of its business".

In a blog post Greenpeace said: "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 okay for a company whose business contributes to climate change to make it past the bag checks."