Prime Minister David Cameron speaks as London Mayor Boris Johnson looks on at an election rally | Toby Melville/WPA Pool /Getty UK referendum ‘a glorified cockfight’ Liberal MEP calls Brexit row ‘pathetic and totally bonkers.’

The British referendum on EU membership is nothing but "a glorified cockfight" between David Cameron and Boris Johnson, the leader of the liberal MEPs, Guy Verhofstadt, told the European Parliament Wednesday.

Verhofstadt, a three-time Belgian prime minister, told fellow MEPs that the battle over Brexit between the two leading Conservative politicians was "pathetic and totally bonkers."

In a discussion on the February 18-19 European Council at which the U.K.'s deal on reforming its relationship with the EU was struck, Verhofstadt said he had seen many ambitious politicians in his time, but Johnson was "taking it to a new level." The mayor of London waited 48 hours after Cameron's deal was struck before declaring himself in favor of an Out vote.

Johnson is the most high profile British politician to join the Out camp, but many in Westminster believe his decision was motivated by a desire to replace Cameron in No. 10 Downing Street rather than a genuinely held belief in Brexit.

Verhofstadt was one of three senior MEPs who took part in the U.K. discussions with EU officials, along with Elmar Brok and Roberto Gualtieri.

Manfred Weber, the German MEP who heads the European People's Party, the largest group in the Parliament, said that with war in Libya, aggression from Vladimir Putin, the refugee crisis and economic problems, "it was hard to see how welfare benefits or the City of London could be considered priorities."

Weber said the British people must know this is a final deal and "there will be no follow-up negotiations."

Gianni Pittella, the leader of the Socialist MEPs, slammed Cameron's "emergency brake" deal that would curb in-work benefits for EU migrants.

"Imagine two young people, Europeans, same job, same work, there is a danger one would have less rights than the other. That is discrimination. I hope this will be very much denied by the Commission in the proposals after the referendum," the Italian MEP said.

Nigel Farage, the leader of the United Kingdom Independence Party, with tongue firmly in cheek, told MEPs that "after much deliberation, I've chosen to opt to vote for us to leave."

The debate was sidetracked by a complaint from Irish MEP Luke Flanagan. Flanagan was giving a speech about rules imposed on Irish banks by the European Central Bank when the chair of the debate was overheard saying "Jesus Christ."

Flanagan, a prominent campaigner for the legalization of cannabis, said that was "insulting" and demanded an apology. Parliament President Martin Schulz said he would look into it.