Land mines have killed at least nine Macedonian soldiers on a road just north of the capital, Skopje. Five other soldiers were injured. The deaths follow heavy fighting overnight near Tetovo.
An army truck struck three land mines about five kilometers north of Skopje, killing the Macedonian soldiers.
An army spokesman said the attack occurred on a regularly traveled road near the village of Ljuboten.
The area has in the past served as a logistics route for ethnic Albanian guerrillas fighting in the Black Mountains northeast of Skopje.
The killings cast a further cloud over international efforts to restore peace to Macedonia, after six months of ethnic conflict.
NATO's ambassador to Macedonia, Jans Jorg Eiff, said the incident should not deter the country from seeking peace, saying, "It is all the more reason to work to stop the violence."
Fresh fighting was reported between government forces and ethnic-Albanian gunmen around the northwestern city of Tetovo. Witnesses say Macedonian attack jets flew over Tetovo Friday, but did not open fire.
Macedonian warplanes on Thursday bombed targets near Tetovo according to witnesses, though the defense ministry denied the reports.
Heavy fighting also was reported in the evening around a Muslim landmark on the west side of Tetovo, with guerrillas and government forces in close-range battles.
Ten army reservists killed in an ambush Wednesday were buried in their hometown, Prilep, in the south of the country. News reports said Hundreds turned out for the funerals, including large numbers of their fellow soldiers.
A peace agreement approved by political leaders on Wednesday is set to be signed in a formal ceremony on Monday if the fighting can be brought under control.
The peace agreement would give ethnic Albanians greater rights, including more representation on police forces, and it gives official status for the Albanian language in areas where ethnic Albanians make up at least 20 percent of the population.