"For security reasons, the authorities have decided to increase the level of border controls," Perparim Kryeziu, a government spokesman, told AFP.
The announcement comes in response to an earlier incident on Wednesday in which Serbia said it had arrested three armed Kosovo police officers on its territory.
Kosovo, for its part, claims that the policemen were kidnapped on Kosovar soil. According to Kosovo police, the group belonged to a unit of the border patrol that disappeared after raising the alarm about an incursion by masked and armed men into the area.
The statements follow weeks of heightened tensions between the countries.
Gone up to high alert
In late May, violence broke out after protesters tried to seize the town hall in Zvecan in northern Kosovo to stop the newly elected rule in the city. The unrest led Serbia to put its military forces on high combat readiness. More than 30 soldiers from the NATO-led international peacekeeping force KFOR were injured.
Kosovo declared independence in 2008, but Serbia has not accepted the secession. In the Serb-dominated northern part of Kosovo, there is great opposition to central government.