An armed ambush in Kosovo's volatile north in September near the border with Serbia killed a police officer, triggering one of the worst escalations in the former Serbian breakaway province, dominated by ethnic Albanians.

Stoltenberg will head to Kosovo on Monday for talks with its prime minister and president before visiting peacekeepers from the Western military alliance deployed there.

The next day he will be in Belgrade for a meeting with the Serbian president, NATO said.

Animosity between Kosovo and Serbia has persisted since a war between Serbian forces and ethnic Albanian insurgents in the late 1990s that drew NATO intervention against Belgrade.

Kosovo, which counts 120,000 Serbs among its 1.8 million people, declared independence from Serbia in 2008, in a move Belgrade has never recognised.

Existing tensions have flared in Kosovo's north for months.

Protests erupted among Kosovo's ethnic Serbs in April after the authorities installed Pristina-allied mayors after widely boycotted local elections in four Serb northern municipalities.

NATO said 93 troops from its KFOR mission were injured, some seriously, in "unprovoked attacks" during the protests. The alliance deployed more personnel to Kosovo in response.

Western powers -- including the United States and the European Union -- have been pressing Kosovo and Serbia to make progress on long-standing efforts to improve ties.

EU leaders failed to convince the two sides to make a breakthrough at lengthy talks in Brussels last month.

During his trip to the Balkans, Stoltenberg will also visit Bosnia on Sunday and NATO member North Macedonia on Tuesday.