BELFAST, Northern Ireland (AP) _ Police arrested two Protestant militants Saturday after a Catholic man was shot fatally through the head, the second such sectarian killing this week in Northern Ireland.

Ciaran Heffron, a 22-year-old university student and part-time worker at Northern Ireland's main airport, was killed as he walked home alone from a pub in the religiously mixed town of Crumlin, 10 miles west of Belfast. A taxi driver found his body dumped outside the town's railway station about 3 a.m.

On Friday, Catholics in Portadown buried 29-year-old Adrian Lamph, fatally shot at his workplace Tuesday in the predominantly Protestant town 30 miles southwest of Belfast.

The unclaimed killings are being blamed on pro-British Protestants opposed to the proposed peace accord for Northern Ireland, which was struck April 10 among eight parties and the British and Irish governments. It must be approved May 22 in referendums in both parts of Ireland.

The paramedic who tried to revive Heffron, David Sands, said the victim was ``shot several times in the head.''

``I've been doing this job for 15 years now. Everyone thinks you get hardened to it, but you don't. In fact it gets worse the more you see,'' Sands said.

``I'm sick, saddened, shocked,'' said Mervyn Ray, a Crumlin councilman for the Ulster Unionists, the major Protestant party that accepts the compromise accord _ but has suffered high-profile defections from its ranks.

The Crumlin slaying came hours after about 1,200 Protestant diehards rallied in the nearby town of Antrim against the accord, which they fear will lead to the eventual demise of Northern Ireland as a Protestant-majority state.

The protesters condemned the central planks of the proposed agreement: a new Northern Ireland Assembly in which major parties, including the IRA-allied Sinn Fein, would have a role in administration; and a new North-South Ministerial Council in which the north's leaders would promote joint policy-making with the Irish Republic.

Representatives of the north's biggest Protestant paramilitary group, the Ulster Defense Association, emphasized their support for the Good Friday agreement at their annual conference Saturday.

The UDA's Ulster Democratic Party gathered east of Belfast at the La Mon House Hotel, scene of one of the Irish Republican Army's worst atrocities _ a no-warning gasoline bomb in 1978 that burned 12 Protestants to death.

Ulster Democrats chairman David Adams warned in a speech to party activists that Northern Ireland could suffer violence ``on a scale and intensity not seen here before'' if Protestants rejected the deal in the upcoming referendum.

The UDA's six-member command on Friday lauded the agreement as likely to strengthen Northern Ireland's 77-year-old union with Britain. The UDA is responsible for slaying several hundred Catholics since the early 1970s, but has maintained a truce since October 1994.

Also Saturday, the London office of British Prime Minister Tony Blair confirmed he would meet Sinn Fein leader Gerry Adams there on Monday.

It will be their fourth meeting in Blair's Downing Street residence since the IRA cease-fire of July 1997, but the first since Sinn Fein helped negotiate the Belfast accord.

Fearful of a damaging split, Sinn Fein leaders have shied from endorsing the agreement until they can demonstrate approval from their party grassroots. Many are disappointed that the deal seeks to reform, rather than abolish, Northern Ireland. Sinn Fein leaders are organizing a special conference May 10 for activists to vote on the accord.