Serbia's negotiator with Kosovo confirmed Saturday a key deal for joint management of their disputed border crossings, after demurring in the wake of a European Union announcement.

Borko Stefanovic told journalists he had been given "additional assurances" on the deal, without specifying what they were.

The EU announced the agreement, seen as crucial to Serbia's bid to win entry to the bloc, on Friday, calling it a vital step in reducing tension on the north Kosovo border.

But Stefanovic had told Tanjug news agency on Friday: "Although we have significantly got our positions close, it remains to put a dot on the 'I'."

The EU's foreign affairs office had said that the parties had reached an agreement on the "EU developed concept of integrated management for crossing points".

"This means that the parties will gradually set up the joint, integrated, single and secure posts at all their common crossing points."

The system, to be gradually implemented as soon as possible, is to be overseen by members of the European rule of law mission EULEX, which combines officials and police.

The EU announcement followed three days of long talks into the late hours as Serbia came under strong pressure from EU nations and NATO to take a proactive role in stemming violence on the border.

A new surge of unrest at the two crossings in recent days left scores injured, including NATO peacekeepers, while threatening to scuttle the fledgling Serbia-Kosovo talks as well as Serbia's dreams of EU membership.

Some 50 soldiers from the NATO-led mission were hurt in scuffles with members of northern Kosovo's majority ethnic Serbs who had blocked roads to the border after Pristina sent in ethnic Albanian customs officials to man the posts.

Albanian-majority Kosovo declared independence in 2008 but Belgrade still considers the territory to be a Serbian province, as do the Serb population.

EU-brokered Serbia-Kosovo talks, which began in March, are aimed at resolving practical day-to-day problems for residents of Kosovo caused by Serbia's refusal to recognise Kosovo's independence.