Rebels ambushed a Russian military vehicle in southern Chechnya (search) and staged hit-and-run attacks against federal positions, killing 16 soldiers and wounding 13 in heavy fighting over the past 24 hours, a Chechen administration official said Sunday.

A sapper unit traveling in a heavy Kamaz truck was blasted by a remote-controlled land mine in the Shatoi region of southern Chechnya on Saturday evening, said the official in the Kremlin-backed administration, speaking on condition of anonymity.

Rebel ambushers then launched grenades and fired automatic weapons at the truck, the official said.

The truck had been at the head of a military convoy returning to base through the mountains of southern Chechnya where many rebels shelter and through which many supply routes run, according to Russian news reports.

In other attacks, rebels fired on federal positions 19 times, killing five soldiers and wounding six, the official said. Clashes also took place in Bamut in western Chechnya, leaving two soldiers dead and two wounded.

Russian troops have been bogged down in Chechnya since 1999, when they returned to the republic following rebel raids on a neighboring Russian region and a series of deadly apartment-house bombings in Russian cities that were blamed on the rebels.

Before that, the Russian army (searchfought Chechen separatists unsuccessfully in 1994-96, leaving the region de facto independent when they retreated.

The rebels, who are outnumbered and outgunned, rely heavily on land mine explosions and ambushes. Russian forces respond with air strikes and artillery fire, and controversial "mopping up" operations where dozens of civilians are detained daily in search of rebel sympathizers.

In the last 24 hours, Russian forces led air strikes over the Itum-Kale and Nozhai-Yurt positions, while artillery pounded the Achkoi, Urus-Martan, Kurchaloi, Shali and Shatoi regions, the Chechen official said.

Meanwhile, two security guards working for the Moscow-supported Chechen administration, led by Akhmad Kadyrov, were fired on as they traveled through Shatoi. Both were killed.