Sinn Fein activists protested outside police stations across Northern Ireland on Saturday after officers raided offices of the Irish Republican Army-linked party in search of stolen British documents.

Northern Ireland's 1998 peace accord suffered strain on another front as police said gunmen from two rival Protestant gangs, the Ulster Defense Association and Loyalist Volunteer Force, resumed a monthlong feud over the profits from drugs trafficking.

A gunman killed a 41-year-old man outside his south Belfast home. Hours later a gunman on a motorcycle shot a 19-year-old in the head but didn't kill him. Although no group claimed responsibility for either attack, police arrested a central figure in the feud -- the UDA's east Belfast commander, Jim Gray -- on suspicion of involvement in the latter attack. Gray was shot in the jaw last week.

Detectives continued to question three Sinn Fein activists and a former British government employee arrested during swoops Friday on homes in Catholic parts of Belfast. Under British anti-terror laws, the suspects could be held for up to a week.

To the fury of Sinn Fein leaders, police also invaded the party's office in Stormont Parliamentary Building, seat of power for the Catholic-Protestant administration and legislature formed under terms of the Good Friday pact.

In Catholic west Belfast, about 50 Sinn Fein members -- including Belfast Mayor Alex Maskey and former IRA commander Joe Cahill -- stood outside a police barracks that has car bomb-proof walls and high netting to deter rocket attacks.

Their placards denounced the police as "storm troopers" who were "attacking democracy," and urged Catholics not to join the predominantly Protestant force, another major goal of the 1998 pact.

Police suspect the former British government employee, who quit his Stormont job in September 2001, of funneling confidential government policy documents to the IRA. The outlawed group has been largely observing a 1997 cease-fire but remains active on several fronts and, police say, continues to gather intelligence for a potential resumption of attacks.

Friday's operations compound police allegations that the IRA masterminded a March 17 raid on the secret files of Special Branch, the police's intelligence-gathering arm. The IRA insists it wasn't involved in stealing files that listed the addresses, phone numbers and aliases of top detectives and informers.

Gerry Kelly, a top Sinn Fein activist, said police had raided Sinn Fein's office at Stormont simply to bolster Protestant demands for his party to be kicked out the coalition.

"They looked around and found nothing," Kelly said.

Michael McGimpsey, a moderate Protestant who serves as culture minister in the administration, said he was "absolutely certain" the police wouldn't have mounted such a controversial operation without having solid intelligence.

McGimpsey noted that his Ulster Unionist Party was already committed to withdrawing from the four-party administration, forcing its collapse, in January if the IRA remained active. The alternative, he said, was for Britain to recommend that Sinn Fein's two ministers be kicked out of the 12-member administration, a long-sought Protestant goal.

He said the top two leaders of the Sinn Fein-IRA movement, Gerry Adams and Martin McGuinness, had failed to prevent the IRA from pursuing a range of violent or shadowy activities in the past year.

"Either Gerry Adams or Martin McGuinness have lost control of their movement, or they're insincere about the peace. But either way, if any of these accusations stand up, Sinn Fein must leave the Executive," he said, using the formal term for the Northern Ireland administration.