Planes dropped mines on roads and blasted rebel strongholds in the breakaway republic, as thousands of terrified refugees continued to flee their homes.

The exodus shows no signs of abating despite the onset of the region's bitter winter and the arrival of the first snows.

The BBC's Orla Guerin: Refugees are fleeing in terror and bad weather

The United States on Monday accused Russia of breaking international rules on war designed to prevent civilian casualties.

Opposition has also come from inside Russia, with the liberal Yabloko party calling on the government to suspend its offensive and begin talks with the Chechen President, Aslan Maskhadov.

But Russian Prime Minister Vladimir Putin rejected any criticism, saying if the militants were not destroyed now, "we will face them a fourth, fifth and a tenth time".

"We are dealing with well-organised gangs of international terrorists," he said after meeting the families of Russian policemen killed on duty.

Click here to see a map of the region

Russian bombers destroyed 10 rebel vehicles, an air defence installation and three militant strongholds overnight, the military said on Tuesday.

A woman falls unconscious waiting to cross into Ingushetia

The bombings targeted the rebel stronghold of Urus-Martan, about 20km (12 miles) southwest of the capital Grozny, and militant camps in a canyon in the region's southern mountains.

Jets also mined two sections of road, and damaged a bridge in the south. Helicopters fired rockets on the northern outskirts of the capital, according to the AP news agency.

The Russian military said it had killed eight militants. But Chechen officials said that at least nine civilians had been killed and up to 50 wounded in attacks on Grozny.

International law

On Monday, US State Department spokesman James Rubin said Russia's military tactics were "not in keeping" with the Geneva Convention and commitments established by the Organisation for Security and Co-operation in Europe (OSCE).

"The costs of this approach are too high - costs in humanitarian terms, damage to Russia's international reputation," he said.

"The indiscriminate use of force ... on innocent civilians is a matter of deep concern to us."

Far from scaling down its offensive, Moscow has said it is sending more tanks and troops to the republic. They will be deployed around Grozny, and Chechnya's second-largest city, Gudermes.

Humanitarian crisis

Nearly 200,000 refugees have fled Chechnya since Russian troops began their advance six weeks ago.

The UN High Commissioner for Refugees said on Tuesday that refugees were streaming into the neighbouring region of Ingushetia at a rate of 4,000 a day.

Georgia, which also shares a border with Chechnya, acceded to Russian demands to seal its frontier at the weekend.

Around 21,000 people in Ingushetia are living in camps and railway wagons.

But despite the desperate conditions thousands of refugees are going back to Chechnya to bring family members to safety.

UNHCR spokesman Kris Janowski said the organisation was ''gravely concerned about the scope of the humanitarian crisis and the mounting toll of Russia's military actions on Chechnya's civilian population".

But he said the volatile North Caucasus region, which includes Chechnya, was still a "no-go" area for international aid workers following a series of kidnappings and attacks.

Moscow says it is trying to wipe out Islamic rebels which it blames for recent attacks in Dagestan and Russia.