08/02/2012 12:41 EDT | Updated 10/01/2012 05:12 EDT

Good host: Amid thawing ties, Cameron takes Russia's Putin to watch Olympic judo match

LONDON - They held talks, then it ended in a fight.

Prime Minister David Cameron joined Russian President Vladimir Putin at the Olympic judo competition Thursday after meeting with him in central London on Syria and trade.

It's not a stretch to describe Putin — an honorary president of the International Judo Federation — as the world's best-known judo fan. Putin has been a judo competitor since his childhood, eventually gaining the rank of black belt.

"I am delighted to be taking the president to the judo, but note that we will be spectators — and not participants," Cameron joked as the men left his Downing Street residence.

The two leaders, who have squared off over the world's response to the violence in Syria, travelled in separate cars to see the judo contests at the ExCel Centre in east London.

Military officers and uniformed police lined either side of the VIP entrances to the arena as they arrived and photographers turned their backs to the competition to make sure to grab the moment. Putin and Cameron were joined by Britain's Foreign Secretary William Hague, who holds a blue belt himself.

London Mayor Boris Johnson joked that he wouldn't be surprised to see Putin try to join the competition

"I hope he will take part — isn't he a dab hand?" Johnson told reporters. "I think that's what people want to see, (Putin) stripped to the waist."

The Russian leader is renowned for his displays of machismo and fondness for posing bare-chested, but this time he stayed fully clothed in the VIP section.

At a 45-minute meeting earlier, Cameron pushed Putin over Russia's refusal to back a tough new U.N. resolution aimed at trying to halt the violence in Syria between President Bashar Assad's regime and anti-government rebels.

Britain called the decision by Russia and China to veto a U.N. resolution on Syria two weeks ago "inexcusable and indefensible."

Their talks came before Kofi Annan said he would step down as the U.N. and Arab League special envoy on Syria amid the diplomatic gridlock.

While no breakthrough on Syria had been expected, Putin said the two leaders had noted that "there are some things that we see eye-to-eye on" over Syria.

"We agreed to continue working to find a viable solution," Putin said, speaking through a translator.

Cameron said — despite their differences — both nations wanted to see an end to the bloodshed in Syria, where thousands have been killed since the uprising against Assad began in March 2011.

"We need to work with them, we need to work on them — as it were — to try to get them to move to support transition in Syria, so that we get rid of Assad ," Cameron later told Sky News television.

"There is some common ground emerging, I think. The Russians can see that what is happening is very bad for the Syrian people but also is not in Russia's interests either," he said.

Relations between Britain and Russia soured over the 2006 poisoning death of dissident ex-Russian security agent Alexander Litvinenko in London. Litvinenko made a deathbed statement accusing Putin of authorizing his killing. Russia has refused repeated British requests for the extradition of the chief suspect in the case, ex-KGB agent Andrei Lugovoi, who denies any involvement.

"That part of the relationship has not thawed, and will not thaw frankly, because what happened was unacceptable," Cameron told Sky News.

The visit came as leading British musicians joined an international outcry over the treatment of the Russian punk band Pussy Riot, whose members were jailed following a protest in Moscow's main cathedral.

The musicians said in an open letter Thursday that the band members were involved in legitimate protest and should not be facing up to seven years in jail. They said "dissent is a right in any democracy."

Cameron raised the case with Putin, but neither leader commented on their discussion.

Turning to an easier subject, Putin praised the London Olympics opening ceremony, which he described as "unforgettable."

"It was quite a spectacle. It was a wonderful holiday, a wonderful feast presented by you to mankind," said Putin.