Late Sunday, protesters parked trucks filled with gravel and other heavy equipment on roads leading to two border crossings, Jarinje and Bernjak, in areas where the majority of the population is Serb.

Kosovo police said they were forced to close border crossings, Reuters writes.

"The general security situation in the northern municipalities of Kosovo is tense," the NATO mission in Kosovo said in a statement to KFOR.

The press secretary of the Ministry of Foreign Affairs of Russia,

, accused the Albanians of increasing tensions, citing "groundless discriminatory rules" introduced by the Kosovo authorities as the reason.

The fact that Pristina requires registration of license plates from Serbian motorists is considered discrimination in Russia and Serbia.

It has been 14 years since Kosovo declared independence from Serbia, but around 50,000 Serbs, mostly living in the north, use number plates and documents issued by Serbian authorities, refusing to recognize the institutions of the capital Pristina.

Kosovo is recognized as an independent state by more than 100 countries, but not by Serbia or Russia.

Prime Minister

said it would give Serbs a 60-day transition period to get Kosovo license plates a year after abandoning efforts to impose them amid similar protests.

The government also decided that from August 1, all Serbian citizens visiting Kosovo must obtain an additional document at the border in order to obtain an entry permit.

Moreover, the Belgrade authorities apply a similar rule to Kasavars visiting Serbia.

But after heightened tensions on the evening of July 31 and consultations with EU and US ambassadors, the Kurti government said it would postpone its plan for one month and begin implementation on September 1.

Earlier on Sunday, the police said that "shots were fired in the direction of the police stations, but fortunately no one was injured."

The communiqué also said that several Albanians were beaten by angry demonstrators who were walking along the blocked roads, and that several cars were attacked.

In the town of Northern Mitrovica, populated mainly by Serbs, air raid sirens sounded for more than three hours.

In the evening, the President of Serbia

, made an address, he asked the Albanians not to persecute the Serbs, and the Serbs not to give in to provocations.

He was quoted by the Serbian publication Alo!

"The Serbian people of Kosovo and Metohija listen less and less to my requests, and my request is to preserve peace at any cost.

I ask the Albanians to stop and the Serbs not to give in to provocations, but I also ask the representatives of strong and big countries that recognized the so-called independence of Kosovo to pay attention to international law and not let their "favorites" cause a conflict.

We will pray for peace and seek peace, but I will say right away that there will be no capitulation, and Serbia will win.

If they dare to persecute, offend, kill Serbs, Serbia will win!

I ask them to keep the peace, and if they don't want it, Serbia will win," said Vucic.

A year ago, after local Serbs blocked the same roads over license plates, the Kosovo government deployed special police forces and Belgrade sent fighter jets close to the border.

Tensions between the two countries remain high, and the fragile peace in Kosovo is supported by the NATO mission, which has 3,770 troops on the ground.

Italian peacekeepers operated in Mitrovica and its surroundings on July 31.

In 2013, both countries committed to start a dialogue with the support of the European Union to try to resolve the outstanding issues, but little progress has been made.