Corruption investigators received allegations this year that ACT police had visited a known criminal detained in the Alexander Maconochie Centre. The officers were alleged to have tipped the prisoner off to sensitive law-enforcement information.

The Australian Commission for Law Enforcement Integrity's annual report shows the officers were eventually cleared, after the watchdog was unable to find any evidence that law-enforcement information had been supplied to the criminal.

But the investigation did highlight several "corruption risks"

relating to how police contacted persons of interest, particularly those detained in the AMC.

The corruption investigation forced ACT Policing to change the way it deals with prison visits. Police on official business at the AMC now have to record the details of their visits.

The Integrity Commissioner said other "accountability measures" were also being considered.

Most of the details of the corruption investigation have been suppressed by the commission to protect witnesses.

No criminal or civil proceedings arose from the investigation.

The commission's annual report, released last week , also reveals ACT Policing has toughened the rules for handling drugs.

The changes were sparked by the sacking of a constable who flushed a bag of tablets, thought to be ecstasy, down a toilet in October 2007.

A security guard at one of Canberra's licensed venues gave the drugs to the officer after finding them on the floor. The constable accepted the drugs without making any note in his notebook, and there were fears he may have kept them for his own use, or to sell.

He was later discovered to have flushed them down a police station toilet.

The constable also failed to declare a relationship with a girl who was a known drug user. And he used police cars as "blue light taxis" to give lifts to friends, and accepted free drinks and preferential treatment from management at clubs that were part of his patrol.

But the commission was unable to find any evidence he had tried to keep the drugs for himself, and cleared him of corrupt conduct.

The constable gave evidence to the commission in his defence, saying he had flushed the drugs because the proper lodgement procedures took too long, and that drug handling guidelines were onerous. "On a busy night like that, there may only be three members on [duty] . . . but to receive drugs it generally takes a car . . . off the road for a period of maybe one to two hours while we exhibit them, lodge them out at – with the Winchester Centre. At the time, getting rid of them ourselves by myself flushing them down the toilet and keeping a car on the road . . . was the reason I did that."

The Integrity Commissioner found that attitude posed a significant "corruption risk" if it was shared by others in the force.

"Such a situation poses a corruption risk whereby the use of 'work-arounds' and avoidance of proper procedure may become accepted and not routinely reported," the commissioner wrote.

The procedures for drug handling have since been improved.