Policemen killed four suspected militants...

The spokesman said that at about 1:00 a.m. Moscow time (22:00 GMT) policemen stopped a car on the Kavkaz federal highway with suspected militants.

"People in the car opened fire on the policemen and were killed in return fire," he said adding that one of them has been already identified as Magomedzagir Vagabov, who was on Russia"s federal wanted list.

Two assault rifles and grenades were confiscated that were in the car, he said.

Russian President Dmitry Medvedev has ordered the Federal Security Service to tighten security in the North Caucasus following a January 6 suicide bomb attack in Dagestan that killed five and wounded up to 19 people.

Russia"s mainly Muslim North Caucasus republics, especially Chechnya, Dagestan and Ingushetia, have seen an upsurge of militant violence lately, with frequent attacks on police and officials.

MAKHACHKALA, January 20 (RIA Novosti)