Chechen rebels opened fire on Russian troops, killing seven soldiers and wounding seven others, an official in Chechnya's Moscow-backed administration said Sunday.

Federal outposts came under fire 18 times over the weekend, the official said speaking on condition of anonymity.

Rebels sprayed a military car with gunfire near the town of Argun, killing two soldiers and wounding one, the official said.

In southwestern Chechnya, a Chechen police officer was killed by gunfire as authorities swept through Urus-Martan on Saturday in search of rebels. The attacker was shot and killed, the official said.

In the Chechen capital, Grozny, an armored military car set off a land mine Sunday, wounding a Chechen police officer and a passer-by. The police chief of Grozny's Oktyabrsky district, Adlan Takayev, was in the car but survived the explosion, the Chechen official said.

Meanwhile, Russian artillery pounded suspected rebel bases and federal forces detained at least 150 people in sweeps, authorities said. Human rights groups have criticized those raids.

Russian officials insist peace is returning to the region in the wake of a referendum in which Chechen voters approved a constitution that binds Chechnya firmly to Russia. However, attacks on Russian troops continue daily, with little sign of a letup.

Russian forces fought a 1994-96 war with Chechen separatists. They returned three years later after several attacks blamed on rebels.