This is the latest in a series of cases at the exclusive Berkshire school, in which several boys have faced severe punishments for drugs-related scandals.

In response to the latest reports a spokeswoman said: "I can confirm that a boy was asked to leave the school earlier this week in connection with a drugs incident."

She declined to give further information, adding: "This is an internal matter, which has been dealt with by the headmaster, who will not comment on disciplinary matters within the school."

Strict on drugs

It is understood the boy, who has not been named, was caught smoking cannabis by Angus Graham-Campbell, housemaster at Common Lane House.

The school refused to confirm the boy's age, but a report in Friday's Mirror said he was in the same lower sixth year as 16-year-old Prince William.

Eton's headmaster John Lewis has taken a strict line on illegal drugs since he took over at the school in 1994.

Mr Lewis, from New Zealand, introduced drugs testing for the boys in 1996.

The move made Eton the highest-profile member of a growing number of independent schools which have adopted testing as a deterrent.

Prowling in grounds

But in March this year two sixth formers were excluded from Eton after a policeman caught them smoking cannabis in Windsor less than one mile from the school.

They escaped with a caution but were automatically expelled because of the school's strict anti-drugs policy.

In 1995 the school threw out one boy and suspended another for possession of Ecstasy. Four sixth formers were arrested after one was found with cannabis.

In November of that same year, a 19-year-old Old Etonian was found prowling in the grounds and arrested on suspicion of possessing drugs with intent to supply.

Thames Valley police said they had not been involved in the latest incident.

A spokesman said: "This is nothing whatsoever to do with us. The school has taken their own actions. They have confiscated and destroyed the offending items and dealt with the matter appropriately themselves."