Russian Nikolay Davydenko said he expected an ATP investigation into his match against Martin Vassallo Arguello in August to take another month.

"I had a meeting with them (the ATP) last month in Frankfurt just after the Davis Cup," he told a news conference at the Kremlin Cup.

"They had two guys from Scotland Yard there, but they're delaying the decision. I think it will be another four weeks."

Internet bookmaker Betfair voided all bets on the match at the Sopot Open in Poland because of what it said were irregular betting patterns with more than $7 million worth of bets placed.

Davydenko won the first set but later retired with a foot injury when his opponent, ranked 80 places lower, was leading 2-6 6-3 2-1.

The ATP said they would have no immediate comment on Davydenko's remarks.

Britain's Andy Murray told Reuters earlier he would speak to ATP investigators at next week's Madrid Masters about his allegations that matches were being fixed.

"I'm not going to name any names," Murray said.

"I've just spoken to quite a lot of the players about that and there's obviously something that needs to be addressed."