Three Kosovo police officers were detained by Serbian forces on Wednesday but officials from Kosovo and Serbia gave different locations for the arrest, accusing each other of crossing the border illegally.

Kosovo Prime Minister Albin Kurti demanded the release of the three officers. He said they had been arrested 300 meters inside Kosovan territory, near the border with Serbia.

“The entry of Serbian forces into the territory of Kosovo is aggression and aimed at escalation and destabilization,” Kurti wrote on his Facebook page.

In response to the detentions, Kosovo’s interior minister, Xhelal Svecla, told reporters he had ordered officers at border crossings to stop all trucks with Serbian plates and trucks carrying Serbian goods.

But Petar Petkovic, the head of the Serbian government office for Kosovo, said the three were arrested “deep inside” Serbian territory.

He told a news conference in Belgrade that the arrest took place in the village named Gnjilica, a few kilometers from the border, and that Serbia was willing to accept an international investigation into the arrest.

The detentions may further fuel tensions in the predominantly Serb northern part in Kosovo which borders Serbia and which has seen violence in recent weeks.

Kosovo declared independence from Serbia in 2008, nearly a decade after an uprising by the 90% ethnic Albanian majority against repressive Serbian rule.

In 1999, a NATO bombing campaign drove Serbian security forces out of Kosovo but Belgrade continues to regard it as a southern province.

Violence flared last month when 30 peacekeepers and 52 Serbs were injured in clashes in four predominantly Serb municipalities in northern Kosovo just outside Serbia.

It erupted after Serbs rallied against ethnic Albanian mayors who moved into their offices following a local vote in which turnout was just 3.5%. Serbs in the area boycotted the election.

The arrest on Tuesday of a Serb identified by the Kosovo Albanian interior minister as an organizer of assaults on NATO peacekeepers during unrest last month stirred more anger in the region and triggered protests on Wednesday.