An explosion ripped through a motel in northeastern Macedonia early Sunday, killing two employees and complicating NATO's efforts to start its mission to collect weapons from ethnic Albanian rebels.

The deadly blast adds pressure on the alliance on the eve of the planned start of its mission, called Operation Essential Harvest. NATO has repeatedly stressed it is trying to build confidence between ethnic Albanian rebels and the government.

The explosives were strapped to the bodies of the two employees found dead in the Macedonian-owned motel in Celopek, six miles south of the predominantly ethnic Albanian city of Tetovo, state television said, quoting police sources who spoke on condition of anonymity.

Celopek is the birthplace of Macedonia's hard-line interior minister, Ljube Boskoski, who is one of the most outspoken opponents of NATO's plans.

Meanwhile, Macedonian government officials made no statement after wrapping up a special security session Sunday on how to respond to NATO's assessment on the number of weapons it plans to collect from the rebels.

NATO plans to collect about 3,000 weapons, Western diplomats have said on condition of anonymity. Macedonia's leaders say that figure is far too low. The government says the insurgents have 85,000 weapons — a claim Western observers say is an attempt by hard-liners within the administration to obstruct the peace deal.

President Boris Trajkovski was to make a decision on how to proceed later Sunday evening, government sources said on condition of anonymity.

But dissension was evident. Prime Minister Ljubco Georgievski emerged from the meeting before it was over making clear his opposition to the disarmament plan. He called NATO's estimates of rebel arms "humiliating."

Both Macedonian security forces and the rebels have agreed to pull back from sensitive areas in order for NATO troops to set up one-day weapons collection points as part of a peace plan, alliance officials said.

The withdrawals "are designed to ensure there is no tension, or the least possible tension, prior to the weapons collection," said Col. Paul Edwards, chief of operations for the mission.

By midday Sunday, however, no withdrawal was evident, and skirmishes continued to threaten the peace deal.

Police reported an exchange of infantry and artillery fire in the Kumanovo area northeast of the capital, Skopje. Police accused rebels of provoking security forces, who "responded adequately."

The alliance hopes to collect about a third of the arms by the end of next week in time for a key meeting to launch the parliamentary procedures called for in the peace plan.

The deal that ended six months of fighting between rebels and government forces envisions a step-by-step process in which rebels will hand over weapons to NATO in exchange for political reforms in Macedonia.

In a gesture of good will, ethnic Albanian rebels released four hostages Sunday in the northern village of Lipkovo. They were handed over to representatives of the International Committee of the Red Cross.