A 14-year-old schoolboy was fighting for his life last night after he was brutally attacked outside his school by a gang of five youths armed with a machete-style weapon.

Police say the gang had waited outside the south-east London school for their victim, who was so badly beaten he had to be airlifted to the Royal London Hospital, Whitechapel, east London, for emergency treatment.

His condition was said to be serious but stable.

The attack at Kidbrooke secondary school, Eltham, left the victim lying unconscious in a pool of blood outside the school gates.

Inspector Kevin Toal from Plumstead said the attackers, all in their teens, were four Oriental-looking boys and one white boy.

Police, who said they were keeping an open mind about whether the attack had Triad links, hope school video cameras might provide clues to the identity of the attackers.

Only one boy made the attack, swinging the weapon down on the victim's head before running off. The boy was treated first at the scene by a passer-by who tried to staunch the flow of blood until an ambulance arrived.

The injured boy was leaving the school shortly after 3.30pm when he was set upon.

The Kidbrooke school head teacher, Ms Tricia Jaffe, said the attack happened at the Holburne Road entrance to the school, as children were leaving at the end of the school day.

The boy's attackers were not pupils at the school, but who they were and where they came from was unclear.

``It happened at the end of the school day. When people are going home, it's very difficult to piece these things together,'' she said.

Three months ago, 16-year-old Learco Chindamo, leader of a Triad-style street gang, was ordered to be detained indefinitely after being found guilty of the murder of headmaster Philip Lawrence outside his London school.

Mr Lawrence was stabbed with a 10-inch knife as he went to the aid of a pupil, outside St George's Roman Catholic school in Maida Vale, West London, at the end of the school day, in December 1995.

Last November, Christopher Gan, 15, who was said to have provoked the attack, was ordered to be detained for three years after being found guilty of conspiracy to cause grievous bodily harm and wounding.

The Old Bailey heard that Gan, a Filipino, had boasted that he was a member of a Triad-style gang.

A police spokesman said yesterday that there was ``nothing to point to'' Triad involvement but added that detectives were keeping an ``open mind as to the motive''.

Police are currently appealing for any witnesses who saw the suspects hanging around the school gates.

Inspector Toal said: ``We shall be beginning door-to-door inquiries and making searches from tomorrow morning and we appeal to anyone who saw this incident to contact us.''