Russian officials said the raids were intended to prevent Chechen-based guerrillas to spread subversion through the North Caucasus, especially in neighbouring Dagestan.

	Chechnya: Round two? Battle for the Caucasus Cat-and-mouse conflict Islamic roots in Dagestan Russia's demoralised army

Chechen commanders have been told by their government to prepare for a fresh Russian invasion. A spokesman for Chechen President Aslan Maskhadov said the republic was preparing a defence plan in case the strikes continue.

Said-Selim Abdulmuslimov said Chechen military units would soon be receiving sealed orders containing details of missions to be carried out if Russia launched further attacks.

Paul Anderson: Russian attacks have raised the spectre of war

On Thursday, Russian planes and missiles bombarded targets in Grozny, destroying a radar station, aircraft and setting an oil refinery in the northeast of the city ablaze.

The Russian RIA news agency reported "suffocating black smoke" over the city and a "roaring wall of fire up to 100 metres high" in the Staropromyslovskiy district.

Witnesses in Grozny said buildings shook as bombs struck an airport ed an airport.

Police in Chechnya said five people were killed in the bombing.

Mobilisation of troops

Over the weekend, Moscow said it had deployed some 30,000 Russian troops in an operation to seal the border of Chechnya.

Russian bombs destroyed aircraft on the ground

Interior forces are reported to be taking up positions in the strategic heights of Chechnya's neighbouring republic Ingushetia. A commander in the region said the move was defensive to prevent Chechen armed gangs from moving into Ingushetia.

The moves coincide with reports of mobilisation of hundreds of Chechen militants on the border.

Increasing numbers of refugees are also reported to be seeking to cross into Ingushetia, fearful of renewed military activity.

'No repeat of civil war'

But Russian Prime Minister Vladimir Putin says there are no plans for a large-scale military operation in Chechnya. He insisted on Thursday that Russia would not be dragged into a conflict similar to the 1994-96 secessionist war that left some 80,000 people dead.

The Russians have been fighting Chechen-led guerrillas in Dagestan who are trying to establish an independent Islamic state.

In the past two months, the Chechens have reported repeated incursions on or near the border with the republic of Dagestan.

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

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