Serbia puts forces on alert after Kosovo police operation in Serb-populated north

BELGRADE/PRISTINA, May 28 (Reuters) - Serbia ordered its security forces on full alert on Tuesday after police in neighboring Kosovo mounted an anti-smuggling operation in a northern region of the country populated mainly by Serbs. The move came amid rising tension in four Serb-populated municipalities in Kosovo's north, which remains largely outside control of Pristina and pledges allegiance to Belgrade. Serbian President Aleksandar Vucic on Monday acknowledged Belgrade had lost control over Kosovo, its former southern province, but warned it would react if Kosovo attacked Serbs there.