Kosovo has closed its largest border crossing with Serbia after protesters blocked it on the Serbian side to support their comrades in Kosovo, Reuters reported.

Since two other border crossings with Serbia have been closed due to similar protests on the Kosovo side since December 10, only three crossings between the two countries remain open.

The latest protest comes hours after Serbia said it had put its army on maximum alert after weeks of escalating tensions between Belgrade and Pristina.

Serbs in Serbia used trucks and tractors Tuesday to set up a new roadblock near the Merdare checkpoint on Kosovo's eastern border, Belgrade media reported.

The Merdar entry point is the most important point of entry in Kosovo for truck traffic.