Bangladesh has accused anti-corruption investigators from the International Cricket Council of allowing a match in a scandal-plagued Twenty20 tournament to go ahead even though it knew it was fixed.

A report from a special tribunal set up by the Bangladesh board said the ICC's Anti Corruption and Security Unit (ACSU) was aware beforehand that a match in the Bangladesh Premier League was going to be fixed but decided to keep organisers in the dark rather than alert them.

"The evidence is clear that the fixed match between DG (Dhaka Gladiators) and CK (Chittagong Kings) played in Chittagong on the 2 February 2013 was played with the consent of ACSU," the tribunal's report said.

"It is obvious that the focus of ACSU was on gathering evidence and not on prevention of (the) fixed match," the report added.

The report was handed to the ICC on June 8. The tribunal, headed by a retired judge, was set up by the board last September after the ICC brought charges against nine people over fixing.

Organisers had hired the ICC's investigators to monitor the BPL after its inaugural edition in 2012 was tainted by similar allegations.

The tribunal has subsequently convicted one of the owners of the Dhaka Gladiators of match-fixing, while three international players pleaded guilty over the 2013 scandal.

Former New Zealand international Lou Vincent pleaded guilty to breaching the ICC's code of conduct for failing to tell authorities when a bookmaker approached him about fixing a match.

Former Bangladesh captain Mohammad Ashraful and Sri Lanka's Kaushal Lokuarachchi have also pleaded guilty.

The report said Dhaka Gladiators coach Ian Pont alerted the ACSU that he had been approached by one of the team's owners about fixing the February 2 match but was instructed to go ahead and play.

ICC spokesman Sami Ul Hasan declined to comment on the report's allegations. "We are reviewing the written judgement and have no comments to make at this stage," he told AFP in an email.

The tribunal said ICC investigators were obligated to inform the BCB of any wrongdoing. "The chairman of ACSU, Sir Ronald Flanagan, expressed his regret about this failure to inform BCB of this significant matter and made a personal unreserved apology on behalf of ACSU for not involving BCB at that stage."