The head of NATO has urged Serbia and Kosovo to ease tensions and revive their efforts to normalize relations after talks aimed at mending ties collapsed amid mutual recriminations this week.

"Not more rhetoric, but we need dialogue. We need to reduce tensions to avoid incidents...and move forward normalizing the process between Pristina and Belgrade," NATO Secretary-General Jens Stoltenberg told reporters after meeting with Kosovar Prime Minister Isa Mustafa in Pristina on February 3.

Kosovo and Serbia, after an attempt at negotiations abruptly broke up without result late on February 1, have engaged in an escalating war of words, accusing each other of stoking ethnic tensions.

Kosovar President Hashim Thaci urged the European Union and NATO on February 3 to warn Serbia against inciting a new conflict in Kosovo and the Balkans.

Serbian Prime Minister Aleksandar Vucic, meanwhile, blamed Kosovo for the collapse of the EU-mediated talks and charged that Pristina is planning to send troops into a part of northern Kosovo that is populated largely by Serbs.*

He rejected calls by Western ambassadors to pull back Serbian police forces from Serbia's border with Kosovo.

NATO still has around 4,500 troops stationed in Kosovo to keep the fragile peace.

*This article has been amended to clarify where Vucic accused Pristina of planning to send troops.

Based on reporting by AP and Reuters