Immigration officials have pinned down and injected tranquillisers into at least two asylum seekers on Christmas Island – all the while insisting publicly that under no circumstances are chemical sedatives used in detention.

In one incident, described in a confidential report as a major use of force, four guards held down a man so two intravenous drips could be inserted in a ”pre-planned attempt to sedate” him.

The actions appear to contradict internal immigration detention guidelines stating ”sedatives must not be used as a method of restraint”.

The Immigration Department also claimed in remarks intended for public release in December 2010, four months after the incident, that sedatives are never used in detention.

”Under no circumstances are chemical agents, including sedatives, tear gas, pepper spray or capsicum spray used in immigration detention,” said the document prepared for what are known as talking points.

The apparent contradiction has been unearthed as part of a new online database of official documents released under freedom of information laws and intended to cast new light on conditions inside detention facilities.

The department maintained this week sedatives are not used as a form of restraint but a spokesman said ”it is still open to health practitioners to administer them”.

But in a second case in May 2011, four guards held a man on his back by his arms and legs while medical staff gave him an injection ”to calm down Detainee and help him sleep”, according to a separate report.

The man had become agitated after he was refused a cigarette. An officer later saw the man having difficulty breathing, and being carried into a medical ward by guards and detainees.

The report does not make clear what occurred in the interim but said the man had continued to be aggressive and had just assaulted a guard.

Around 20 minutes later he had quietened down enough and was found to have a few grazes to his arms and knees.

The two cases are among hundreds of reports compiled in the Detention Logs website, intended to make searching the reams of declassified material simpler.

Paul Farrell, a Sydney-based journalism student and one of three founders of the database, said the online search would better inform debate about detention policy.

The database draws on copious material the Immigration Department posts online but in a format not readily accessible to electronic searches.

”We thought there was a real need to increase transparency in detention centres,” Mr Farrell said.

The Immigration Department spokesman said under appropriate circumstances a medical practitioner may decide to sedate a highly agitated person behaving in a way that was a threat to their health and wellbeing.

The original release of this article first appeared on the website of Hangzhou Night Net.