Visitors to a London portrait gallery were treated to an impromptu performance on Sunday when three semi-naked climate activists were doused with mock crude oil in a protest against arts sponsorship by British oil company BP.

The unauthorized stunt at the National Portrait Gallery capped a two-week wave of actions by civil disobedience movement Extinction Rebellion, which led to more than 3,300 arrests in London and cities around the world, the group said.

Activists spread a white sheet over the floor of the main hall of the gallery¡¯s Ondaatje wing before two women and a man wearing only skin-colored underwear adopted fetal positions on the covering.

Protesters then slowly doused the prone performers with washable black liquid as activist Eden Rickson read a poem asking the gallery to stop accepting sponsorship money from BP.

¡°We cannot be artists on a dead planet. ... Yet right now the National Portrait Gallery is tied to a company brutally funding the end of our world,¡± Rickson said.

¡°With compassion, we ask you to change. Oil means the end, but art means the beginning.¡±

The National Portrait Gallery said BP¡¯s support for its Portrait Award encouraged the work of artists around the world and enabled free admission to an exhibition, which had drawn more than 300,000 visitors this year.

¡°The ongoing debate around BP¡¯s sponsorship of the arts raises important questions about both the environment and arts funding, and we are listening carefully to voices on all sides,¡± the gallery said in a statement.