Andy Murray was accused last night of being corrupt by Nikolay Davydenko, the Russian player at the centre of the match-fixing scandal that has engulfed the sport. The world No 4 was reacting to comments made by Murray this week in which the British No 1 said that “everyone knows it [match-fixing] goes on”.

“If Murray says that he knows, that means that he gambles himself,” Davydenko said after reaching the quarter-finals of the Kremlin Cup in Moscow. “Because people who start talking out loud have their fears disappear. And they know that if they speak out loud, it means that they are free, they have not done it.

“Since Murray was describing in detail how it goes on, it means he went deep into it. As if he was never involved, but he knows how it works in detail. It was folly of him to say this.”

Rafael Nadal, the world No 2 from Spain, was also dismissive of Murray’s outburst. “I doubt Murray knows more than anyone else – he’s gone overboard and there are no fixed games,” he said.

Murray, whose recent revival was brought crashing to a halt by Janko Tipsarevic, of Serbia, in Moscow yesterday – in a 6-4, 7-5 defeat – was summoned by the ATP after he added fuel to the rumours that corruption is rife in the sport. But yesterday he was forced to clarify his words. “The comments that I made with regards to betting in tennis have been taken out of context and I would like to clarify them,” Murray said. “When I said ‘everyone knows that it’s going on’ I meant that everyone has probably heard that three or four players have spoken out about being offered money to lose matches – which they refused.

“I am glad that the tennis governing bodies are coming together to set up an anticorruption unit to address this and I stand fully behind this effort. Tennis has been a part of my entire life and it is a privilege to compete at the highest levels of the sport.”

Murray had beaten Tipsarevic in the Moselle Open in Metz, France, last week, but the Scot started sluggishly yesterday and failed to muster a break point in the opening set against the world No 68. Murray, who is ranked No 18 in the world, improved in the second set and moved into a 5-2 lead, but Tipsarevic reeled off the next five games and earned a meeting with Radek Stepanek, of the Czech Republic, in the last eight.

Betfair, the internet exchange, declared all bets void on the match between Davydenko and MartÍn Vassallo Argüello, an Argentinian ranked 83 places lower than him, in the Orange Prokom Open in Poland in August and handed details of suspicious betting patterns to the ATP.

As a result, the first tennis Integrity Unit is in the process of being set up by the four stakeholders in the sport, the ATP, the WTA, the ITF and the grand-slam tournaments.