Sign up now for FREE unlimited access to Reuters.com Register MITROVICA, Kosovo, July 31 (Reuters) – Kosovo police said they had closed two border crossings in the restive north after local Serbs blocked roads and fired at police in protest at an order to change Serbian car license plates to Kosovo plates. within two months. Fourteen years after Kosovo declared independence from Serbia, some 50,000 Serbs living in the north use license plates and documents issued by Serbian authorities, refusing to recognize institutions under the capital, Pristina. Kosovo has been recognized as an independent state by more than 100 countries, but not by Serbia or Russia. Prime Minister Albin Kurti’s government said it would give Serbs a 60-day transition period from August 1 to get Kosovo license plates, a year after abandoning an effort to enforce them amid similar protests. Sign up now for FREE unlimited access to Reuters.com Register The government also decided that from August 1, all citizens from Serbia visiting Kosovo will have to obtain an additional document at the border to be granted entry. A similar rule is applied by the authorities in Belgrade for Kosovars visiting Serbia. Protesters parked trucks filled with gravel and other heavy machinery on roads leading to the two border crossings, Jarinje and Bernjak, in a Serb-majority area. As a result, Kosovo police said they had to close the border crossings. “We urge all citizens to use other border crossings,” police said on their Facebook page. Police said shots were fired “in the direction of police units, but fortunately no one was injured.” It also reported that angry protesters beat several Albanians who were passing through the blocked streets and that some cars were attacked. Air raid sirens sounded for more than three hours in the small town of Northern Mitrovica, which is mainly inhabited by Serbs. A year ago, after local Serbs blocked the same roads over signs, the Kosovo government deployed special police forces and Belgrade flew fighter jets near the border. Tensions between the two countries are now at their highest level in years and the fragile peace in Kosovo is being maintained by a NATO mission that has 3,770 troops on the ground. Italian peacekeepers were visible in and around Mitrovica on Sunday. The two countries committed in 2013 to a European Union-sponsored dialogue to try to resolve outstanding issues, but little progress has been made. Sign up now for FREE unlimited access to Reuters.com Register Report Fatos Bytyci. edited by Philippa Fletcher Our Standards: The Thomson Reuters Trust Principles.