The Latest on tensions between Serbia and Kosovo (all times local):

9:55 a.m.

Kosovo police and media say two officers have been injured during a police action in the north of the country that has triggered tensions with Serbia.

A statement said Tuesday's action followed a months-long investigation of criminal groups involved in smuggling, abuse of power, bribery and illegal trade. The lives of the injured officers are not in danger.

Police faced resistance, especially in the commune of Zubin Potok, where they arrested the top policeman, an ethnic Serb. Local Serbs tried to block the road but police broke through.

The police statement said those arrested Tuesday included several police officers and citizens, but didn't specify how many.

Agim Bahtiri, the ethnic Albanian mayor of the commune of Mitrovica, said the operation was against no nationality "but those people who have done harm."

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8:50 a.m.

Serbia has ordered its troops to full alert after reports that Kosovo police entered Serb-populated regions of the former Serbian province.

Serbia's state TV said Tuesday that Kosovo's special police "burst into" northern Kosovo and made several arrests. There was no confirmation of the action from Pristina.

Serbian government official Marko Djuric says the Kosovo police action is designed to intimidate and expel Serbs from Kosovo and presents a "not only a threat to stability but the most direct threat to peace."

Serbia lost control over Kosovo after a NATO intervention in 1999. It does not recognize Kosovo's 2008 declaration of independence.

State TV says Serbian President Aleksandar Vucic ordered a full state of alert for Serbian troops.