TWO people, a 29-year-old woman and a potential recruit, were killed when an anti-tank grenade slammed into a Hell's Angels party early today.

Fifteen other people were injured, some severely, in the bloodiest attack of a two-year feud between the Hell's Angels and Bandidos gangs in Denmark, Norway, Sweden, and Finland.

The feud has left nine people dead and at least 45 injured and police were on the alert for revenge attacks.

The woman killed today, Janne Krohn, had apparently attended the party out of curiosity and was the first person outside biker circles to die.

The 3am blast shook the residential area around the gang's fortress-like headquarters. Police said the grenade - a Swedish-made shoulder-launched AT-4 - was fired from the roof of a building about 70yd behind the compound; a second grenade was found there. No arrests had been made by this evening.

The Hell's Angels are usually hostile to outsiders, but had put up posters inviting local people to their annual ``Viking party'', apparently in an attempt to mollify outraged neighbours frightened by the feud's spiralling violence.

Under pressure from residents, Copenhagen's mayor last month ordered the gang to leave the compound, which it rents from the city. However the gang refused to go.

Police said Krohn had no known ties to the Hell's Angels.

``We don't know precisely why she joined the party. She may have reacted to the posters,'' said police commissioner Ove Dahl.

The other person killed was 39-year-old Louis Linde Nielsen, whom police said was being considered for membership in the gang. Among the injured were Hell's Angels' Danish president Christian Middelboe.

When the grenade hit the building, about half the 150 people at the party were congregated around a bar. The injuries were from shrapnel or the extremely high heat such grenades unleash.

After the blast, a number of weeping young women left the compound as ambulances sped to hospitals and the stench of burning rubber hung in the air.

``The idiots got us,'' screamed one biker as he stormed through a nearby crowd.

Prime Minister Poul Nyrup Rasmussen said the attack was ``abominable''. Justice Minister Bjoern Westh visited the scene with top police officials, and police began nationwide surveillance of clubhouses and homes of members of both gangs.

The feud has increasingly frustrated and disgusted officials in the Nordic countries.

In recent weeks, three other attacks with anti-tank grenades were launched on Hell's Angels clubhouses in Sweden. The grenades are believed to have been stolen from an army depot.

It is unclear what started the feud in the Nordic countries between the Texas-based Bandidos and the California-based Hell's Angels. Police suspect a battle for drug and crime markets.

The violence began in February 1994 with the murder of a Hell's Angels ally in Helsingborg, Sweden. This year, the violence has increasingly endangered bystanders, notably in March when Hell's Angels opened fire on Bandidos at the international airports in Copenhagen and Oslo. One Bandido was killed.

On Thursday, four people were injured when an anti-tank grenade was fired at a Hell's Angels clubhouse in Malmo, Sweden. Another clubhouse, near Helsingborg, was hit twice by grenades last month.-AP.