Cricket's corruption investigation was in ruins last night when the International Cricket Council's anti-corruption unit returned to London after failing to persuade the crooked Indian bookmaker, Mukesh Gupta, to provide a sworn testimony against England's Alec Stewart and a host of other leading international stars.

Gupta's refusal to co-operate will force Sir Paul Condon's corruption investigators to abandon a raft of worldwide inquiries, with Stewart likely to be officially proclaimed innocent by the England and Wales Cricket Board by the start of next month's Ashes series.

Insufficient evidence is also set to end investigations into the West Indian, Brian Lara, Australia's Mark Waugh, the Sri Lankan pair Aravinda de Silva and Arjuna Ranatunga, and the former New Zealand captain, Martin Crowe, and could mean that the Condon inquiry closes, at a cost of £3.5 million sterling, without proving any allegations.

"The anti-corruption officers have arrived back in England today," an ICC spokesman said yesterday. "All of their investigations are confidential and we cannot comment upon the success or otherwise of their visit."

Condon gave Gupta a July 1st deadline to agree to "stand up and be counted" in legal or disciplinary proceedings, as the emphasis switched markedly, at an ICC meeting at Lord's on Monday, from the urge to root out past offenders to building a secure framework in which match-riggers could not operate in the future.

Gupta's lawyers refused point-blank representations from anti-corruption officers for a further meeting. Condon's team was reduced to an impromptu visit to his jewellers' shop in New Delhi, only to be informed by his father, Kishan Mohan Lal, that he was away on tour and "would not be back until Tuesday".

Indian police chiefs had anticipated their failure to persuade Gupta to become the ICC's principal witness.