Clown Roman Stefanyuk performs outside the Houses of Parliament prior to a parliamentary reception in March 2011 hosted by the Association of Circus Proprietors. British lawmakers agreed Thursday to ban the use of wild animals in circuses, in a non-binding decision that will nevertheless embarrass ministers who insist there are legal obstacles to such a move.

LONDON (AFP) – Wild animals could be banned from circuses in Britain if a cross-party alliance of MPs succeeds with a call on Thursday for government action.

MPs will vote on a motion brought forward by backbenchers from the three main parties proposing a ban.

The campaign to stop the use of animals has gathered momentum, with an open letter by a group of celebrities to the Prime Minister on Wednesday urging the government to act.

The vote on the backbench motion will not be binding on the government, but if passed will put extra pressure on ministers.

Agriculture Minister Jim Paice has so far ruled out an outright ban on wild animals in circuses, partly because the government fears being sued by circus owners using human rights laws.

The open letter to David Cameron was organised by campaign group Animal Defenders International (ADI) and signed by high-profile names, including actor Brian Blessed, comic Ricky Gervais and Queen guitarist Brian May.

It said a system of stricter regulations favoured by ministers would not be effective in protecting circus animals.

"The coalition government's decision is completely at odds with public and parliamentary will," it says.

"Every legal obstacle that the government has recently put forward has now been knocked down."

ADI says it has received legal advice that an outright ban on the use of wild animals would not breach the Human Rights Act or the EU Services Directive.

X Factor diva Leona Lewis has also joined the fight, writing a letter to her MP Diane Abbott (Hackney North and Stoke Newington).

She said: "I am shocked and outraged that there needs to be a debate about whether it is OK for wild animals to perform tricks in the big top."