"We will be looking for further confirmation. But if true, that would be a welcome step," State Department spokesman Matthew Miller told reporters.

"We continue to be concerned about the cycle of rising tensions and sporadic violence in northern Kosovo and encourage both parties to return to the EU-facilitated dialogue," he said.

The White House on Friday went public with concerns about what it said was an "unprecedented" Serbian military build-up on the heels of deadly clashes in northern Kosovo, whose independence from Serbia is not recognized by Belgrade.

Serbian army chief of staff General Milan Mojsilovic told reporters in Belgrade on Monday that troops along the border with Kosovo had been cut from 8,350 and 4,500 and voiced surprise at the "deep concern of some," saying similar actions took place during previous "security crises."

Miller stood by last week's US warning, saying that Washington had detected higher troop numbers that caused concern.