The request for a Queensland indemnity for dead prison informant Ray Denning was "a reward" for past assistance in NSW and Victoria including his role in the wrongful jailing of Tim Anderson for the Sydney Hilton Hotel bombing, a NSW anti-corruption body has found.

The NSW Independent Commission Against Corruption (ICAC) report on police and prison informers said Denning had confessed to two Queensland armed robberies - the 1981 robbery of $327,000 from Transurety Ltd, and the July 1988 robbery of $44,000 from a Zillmere bank.

However in June 1990 Queensland Attorney-General Dean Wells signed an indemnity protecting Denning against prosecution following approaches to Mr Wells by Queensland Police Inspector Ron Pickering who had been lobbied by NSW authorities.

The ICAC report, released in January, had not been debated in Queensland for fear of discrediting Denning as a witness and interfering with an upcoming trial involving three armed robbery charges.

Denning's death and the Director of Prosecution's decision last week to drop charges involving him as a witness in that trial has made a full discussion possible.

In 1990, the Queensland Government refused to give details of Denning's indemnity and the Queensland Director of Prosecutions argued in the NSW Supreme Court that it was not in the public interest to release the information.

ICAC's report, however, includes a letter dated 13 November 1989 from NSW Task Force Detective Inspector Aarne Tees to Pickering which reveals that Denning's assistance in NSW and Victoria was the prime motive for seeking an indemnity to shield Denning against prosecution in Queensland.

In his letter, Tees said: "It is of vital importance to us that Denning be granted an immunity in Queensland in respect to the offences he committed up there.

"His continued co-operation both in this State and in Victoria is essential if we are to succeed in convicting persons such as Anderson, Mercouri and others who have been responsible for some of the worst crimes committed here and in Victoria," Tees said.

Although Denning's evidence against Anderson was discredited, Denning remained an indemnified witness in Queensland and it is understood he gave evidence to Queensland police on several armed robberies.

In his report, ICAC Commissioner Ian Temby, QC, said: "I conclude that Tees gave Denning substantial assistance in obtaining the indemnity, which was a matter of importance to Denning.

"I further conclude that such assistance was a price paid in order to secure Denning's continued co-operation," Mr Temby said.

A spokeswoman for Attorney-General Dean Wells yesterday said the approach from NSW was only part of the evidence Mr Wells had when deciding whether Denning should have a Queensland indemnity.

However Queensland Council for Civil Liberties president Terry O'Gorman called on Mr Wells "to release all correspondence between him, the Director of Prosecution, and Police Forces particularly NSW in relation to the indemnity's granting.

"There is no legitimate basis for that to be refused now that Denning is dead," Mr O'Gorman said.

Police Union president Senior Sergeant John O'Gorman called for stricter safeguards in the granting of indemnities and the use of evidence by criminal informants.

Snr Sgt O'Gorman said police faced being `verballed' by informants.

"The accepted interpretation of verballing has always been the coppers claiming people said things they didn't say. There's as much evidence of the reverse of that," Snr Sgt O'Gorman said.