The move came as Russian warplanes continued to attack suspected guerrilla bases near the border between Chechnya and Dagestan.

	Who is to blame? What Russia can do Timeline: The blasts which shook Russia

Russia's NTV said a large number of armoured vehicles and artillery pieces had been sent to the border as federal troops "prepared to seal the administrative border with Chechnya."

Russian forces are also reported to be taking up positions in the Stavropol region of Dagestan and in the neighbouring territories of Ingushetia and North Ossetia.

The BBC's Stephen Dalziel: The army is putting in airborne forces and marines

The Russian parliament endorsed plans to continue air strikes against Chechen rebel bases on Friday in a closed-door meeting with Prime Minister Vladimir Putin.

A Russian military spokesman told the Itar-Tass news agency that the latest raids were intended to prevent further attacks on Dagestan by Chechen-based guerrillas.

The military action follows steps taken to beef up security inside Russia, following a series of bombings in which over 300 people were killed.

Air and ground assault

A Russian military spokesman told reporters that Islamic insurgents in Chechnya had suffered major losses following air strikes by fighter jets and helicopter gunships.

Russia has sent reinforcements to Dagestan in recent weeks

"Preventive strikes on bases and concentrations of gunmen frustrated their plans of a new invasion into Dagestan," he said.

Chechen officials said, however, the air attacks hit villages and civilians.

Security alert

Russian security forces have been maintaining a high profile on the streets of Moscow following the recent bomb attacks on residential buildings.

Police are carrying out identity checks, apparently concentrating on people whose appearance suggests Caucasian origins.

Moscow blames the rebels for the blasts, an accusation denied by the Chechen authorities.