POLICE have warned a prankster could kill after four town centre revellers collapsed when drugs were slipped into their drinks.

Three men and a woman were rushed to Burnley General Hospital after drinking at various Burnley centre pubs and nightclubs -- all suffering varying degrees of collapse and nausea.

Although Burnley Health Trust said their conditions were not life-threatening, police today warned: "The person who has done this could kill."

Blood tests are being analysed to discover what caused the alarming symptoms to the victims who are not known to be or admit to being drug users.

The hospital admissions, between 10.30pm on Saturday and 12.30am yesterday follow on from a similar alert the previous Saturday when four people were rushed to the hospital suffering from suspected drug overdoses -- and three of them were left fighting for their lives.

Two of the people had taken the tranquilliser GHB, known as GBH.

Police later warned clubbers and party revellers to beware a batch of Ecstasy tablets with a Versace motif and announced their were working closely with local clubs to crack down on drugs in licensed premises.

Officers say the lack of any connection between drugs use and this weekend's victims leads them to conclude that their drinks were tampered with. Police swooped on licensed premises, asking managers to warn drinkers, after an officer found the first victim in a state of collapse in a town centre street and patients in similar conditions started arriving at the hospital.

A Lancashire police spokesman today appealed for the malicious prankster to stop.

"Although there have been no serious affects as yet -- no one has been in a critical or near critical condition -- only time will tell when a victim, suffering from something that this stuff affects, causes them to collapse and die."

He added: "It is not a joke. It is not funny -- please desist."

Town centre licensees voiced anger and concern over the weekend's "spiked drinks" incidents and warned customers: "You just can't afford to put your drinks down these days -- don't do it."

Sidewalk 53 bar and nightspot manger Philip Caine said the Saturday night cases in which four people were rushed to hospital in semi-collapsed conditions after drinking at town centre bars, came as no surprise and revealed four people close to him -- two of them his own staff -- had been victims of drugs-in-drinks incidents in recent weeks.

"One young lady passed out in a taxi after visiting a nightclub, luckily a girlfriend was with her.

"Another girl felt seriously ill in the same club, but managed to make it back here where she collapsed at the top of the stairs," he said.

"I have no doubt drugging drinks is far more common than we think, it is happening a lot.

"It may be the work of perverted jokers, but there could be far more sinister reasons -- you must always be on guard."