AN investigation was under way last night after a 14-year-old boy died of a suspected drugs overdose at a residential school after returning from weekend home leave.

The teenager, who has not been named, was a pupil at Kerelaw Secure Unit in Stevenston, Ayrshire.

It is understood the youngster returned to the specialist unit on Sunday night after spending the weekend at his home in the Knightswood area of Glasgow.

A spokeswoman for Strathclyde Police said staff had been unable to waken him yesterday morning. He was taken by ambulance to Crosshouse Hospital in Kilmarnock, but was found to be dead on arrival.

The spokeswoman said that following a post-mortem examination yesterday further tests were needed to establish the precise cause of death.

''Staff at the home raised the alarm when they failed to rouse the boy in his room on Monday morning after he returned there the previous evening after a weekend at home.

''Police inquiries into his death are continuing. However, there would appear to be no suspicious circumstances and a report will be submitted to the procurator fiscal,'' she said.

''One line of inquiry is the possibility that the death may be drugs related. The boy's parents have been informed.''

The sudden death is the latest in a long line of incidents at the home which have embarrassed officials at Glasgow City Council, which manages the unit.

Kerelaw was at the centre of allegations of drug taking and underage sex in 1996 and the council's then deputy head of social work, Ian Gilmour, admitted drugs were a problem in the city's secure units.

A council spokesman said an inquiry had been launched into the death, which had left staff deeply shocked.

He said: ''Any death of this nature is very distressing. Social workers are currently working with police to establish the circumstances surrounding his death and parents have been informed.''

He added: ''Staff have consistently strived to improve standards at the home since the report last year.''

Children are sent to the school by social work departments if they have a record of criminal behaviour or are felt to be severe risks to themselves or others.

Kerelaw, which cares for children with social, emotional, and behavioural problems, has housed some of Scotland's most disturbed young criminals.

Former residents include the playground killer Barbara Glover, who was sent to the unit after being found guilty of murdering schoolmate Diane Watson in Dennistoun, Glasgow.

Richard Keith, who battered and drowned three-year-old Jamie Campbell in Drumchapel in 1990 when he was just 11, was also locked up in the home.

Following the drug allegations three years ago the centre came under further criticism last January from government inspectors who highlighted failings in its education system.

According to the report from Her Majesty's Inspectorate, Kerelaw failed to raise educational standards of the children in its care and was criticised for allowing pupils to smoke in the building.