Forensic tests are being carried out to determine if the mystery drug that struck down 11 partygoers in three Dublin houses at the weekend was the potentially lethal sedative liquid ecstasy.

The tests may be completed later today. Senior officers said last night that initial reports identifying the substance as “Liquid E”, a medical depressant which has become an illegal “rave” drug, were premature.

Officially known as GHB, its use here has been confined mainly to parties and there have been no major seizures of the drug. But gardai warned that it could kill when mixed with alcohol.

And they have advised anybody who attended the parties at three different addresses in Annaly Court in Ongar, west Dublin, in the early hours of Sunday, to seek medical help.

A total of 11 people received treatment after becoming ill at the party. Three men were kept in the intensive care unit of Connolly Hospital, Blanchardstown, with suspected overdoses, but were discharged yesterday evening.

The others were sent home after being checked by hospital staff on Sunday.

Meanwhile, gardai last night stepped up their inquiries to find the source of the drugs.

Officers said they had established that drugs and alcohol were consumed in at least one of the houses and they were examining the possibility that some partygoers pooled their money to buy more drugs after the initial supply had been exhausted. But the source of the drugs has not yet been established.

Detectives hope to carry out more detailed interviews with the victims after they have fully recovered in an effort to find out who bought or brought the drugs to the party.