Image copyright Getty Images Image caption The painting depicts two police officers as pigs, and a protester as a wolf

A student painting depicting race riots and protests in Ferguson has been removed from the halls of the US capitol building, the BBC has learned.

The artwork, which depicted police officers as pigs, had been removed several times by Republican congressmen only to have the Democrats remount it.

It has now been permanently removed due to a rule banning depictions of "contemporary political controversies".

Riots erupted in 2014 after the death of a young black man in Ferguson.

Michael Brown, 18, was unarmed when he was shot by Officer Darren Wilson leading to days of tense stand-offs between protesters and heavily armed police.

Image copyright Getty Images Image caption Police in Ferguson were accused of using excessive force to respond to protests

The painting by David Pulphus, a high school student from Missouri, hung among hundreds of paintings on Capitol Hill for months before coming to the attention of conservative news outlets.

The work sparked outrage from Republicans and police advocacy groups, with one congressman calling it "a slap in the face to the countless men and women who put their lives on the line everyday on behalf of our safety and freedom".

Image copyright Getty Images Image caption Democrats continued to re-hang the painting, as Republicans kept taking it down

Republican Congressman Duncan Hunter of California then took matters into his own hands, removing the painting without permission and delivering it to Congressman Lacy Clay, who represents the student's congressional district.

Mr Clay, along with members of the Congressional Black Caucus, then returned the painting to its original location, only to have it removed again by Republican members of congress.

The tit-for-tat continued for days, until eventually the Architect of the Capitol - which controls works of art in Congress - ruled that it had violated rules for the student art competition because it depicts a subject of "contemporary political controversy".

Mr Clay's office vowed that the congressman still has "much to say" about the controversy and accused Republicans of trying to suppress free speech "with their own brand of retroactive, vigilante censorship".