An election in Kosovo designed to help end years of de facto ethnic partition was marred by violence and intimidation by Serb hardliners yesterday, undermining a fragile EU-brokered pact between the Balkan country and former master Serbia.

Two hours before polls closed in the ethnically-divided town of Mitrovica, a volatile Serb pocket of northern Kosovo, masked men burst into three schools housing polling stations on the Serb side, lobbing tear gas and smashing ballot boxes.

Participation of the north Kosovo Serbs in the Kosovo-wide council and mayoral elections is central to an agreement reached in April to integrate the 40,000-50,000 Serbs living there with the rest of Kosovo, which is majority Albanian and declared independence from Serbia in 2008.

Serbia had called on Serbs in northern Kosovo to take part for the first time, with the EU holding out the prospect of membership talks – slated to begin in January – as a reward for Belgrade’s support for the process.

A woman was hurt when she jumped off a window

But on the mainly Serb side of Mitrovica, a former mining town split along ethnic lines since Kosovo’s 1998-99 war, turnout was just seven per cent at 3pm, compared with 32 per cent Kosovo-wide.

The low turnout and violence was a clear indication of the scale of resistance among north Kosovo Serbs to integration with the rest of Kosovo, and underlined the challenge facing the EU in implementing the April accord.

Voting in north Mitrovica was halted after the attack at around 5pm.

Election officials fled and EU police in armoured vehicles spread out through the neighbourhood as helicopters flew over the town.

The Organisation for Security and Cooperation in Europe (OSCE), which is helping manage the election, pulled out 60 of more than 200 staff from the area.

“The election will not resume tonight or tomorrow and the question is whether it will resume at all,” said Oliver Ivanovic, a candidate for mayor of north Mitrovica. He said a woman was injured when she jumped out of a window.