Serbia has warned it will defend "every inch" of what it claims as its territory in neighbouring Kosovo, BBC News reports.

President Tomislav Nikolic accused Kosovo of seeking a war, after a train painted in Serbian colours and the words "Kosovo is Serbia" was prevented from crossing the Kosovan border.

Kosovo saw the train as a deliberate provocation.

As tensions grew, Nikolic said that he would be willing to send the army to defend Serbs in Kosovo, if necessary.

Kosovo, historically a province of Serbia, declared independence in 2008. It is recognised by the US and most EU countries but not by Serbia or its ally Russia.

The train - heralded as an important transport link by Serbia - was the first direct link between the Serbian capital, Belgrade, and Mitrovica, in northern Kosovo, since 2008.

Many of the remaining Serbs in Kosovo live around Mitrovica.

Serbia said the slogan "Kosovo is Serbia" in many languages was a celebration of its cultural heritage, as were the Serbian Orthodox religious symbols adorning the inside, and the liberal use of the Serbian national colours.

The incident has heightened tensions, causing protests by ethnic Serbs in Kosovo, and prompting Nikolic to comment that the two nations had briefly been "on the brink of conflict".