NATO Secretary-General George Robertson visited Macedonia Wednesday to take a first hand look at Operation Essential Harvest. Alliance officials suggested for the first time that the 5,000 NATO troops in Macedonia might have to stay beyond their 30-day timetable.

A delegation of top NATO officials arrived by helicopter Wednesday at a military base in southern Macedonia. They came to see the results of two days of collecting weapons from ethnic Albanian guerrillas.

About 400 rifles and a handful of rocket launchers and mortar tubes were spread out for inspection by NATO Secretary General George Robertson, his special envoy to the Balkans Pieter Feith, and NATO's outgoing ambassador to Macedonia, Hans Joerg Eiff.

All three said they were satisfied with the results of the alliance's disarmament operation so far, and praised the contingent of Greek soldiers handling the storage and disposal of the weapons. The commander of British troops taking part in the mission, Brigadier Barney White-Spunner, said 80 percent of the arms collected were in his words, "perfectly serviceable."

The alliance aims to collect 3,300 weapons in its 30-day operation. But many Macedonians consider that target too low. Government leaders insist ethnic Albanian fighters are holding up to 85,000 weapons.

Asked by reporters if NATO would complete its mission by its self-imposed deadline of September 26, Mr. Robertson said he was confident it could do so. However, he left the door open to expanding both the scope and time frame of the mission, saying that would be up to NATO's political leaders.

Diplomats and commentators have expressed skepticism that bringing peace to Macedonia after six months of guerrilla warfare could be done in only 30 days.

Ambassador Eiff said the beginning of Operation Essential Harvest was in his words, "the easy part." He cautioned that as the process of parliamentary ratification of a peace agreement advances, mutual distrust between the government and rebels could make it difficult to conclude the deal. He said without the presence of NATO on the ground, there could be, in his words, "trouble from both sides."