A major battle -- probably the biggest in the war so far -- is underway between Najaf and Karbala in Iraq, CNN reported early Wednesday morning [India time].

 Up to 300 Iraqis may have been killed in the fighting, it quoted Pentagon officials as saying.

Due to a severe sandstorm in the region, coalition warplanes are unable to help the ground troops, who have encountered a fierce resistance from the Iraqis, it said.

The Iraqi troops may have destroyed some US combat vehicles, CNN quoted Pentagon officials as saying.

The Iraqis have tried to hit the US forces with rocket-propelled grenades, BBC reported.

A fierce fight is also on in the city of Nasiriya, CNN said.

Some American troops and Iraqi civilians have been killed there, it quoted US officials as saying.

US Marines, according to CNN, have captured nearly 170 Iraqi soldiers holed up in a hospital in Nasiriya.

Down south, there has been a civil uprising against the ruling Ba'ath party in Basra, according to reports.

British commanders, who are outside Basra, told Juliet Bremner, a correspondent with the ITV network, that they have seen groups of 40-50 people protesting at various locations, according to CNN.

"The ruling party responded by firing mortars at the crowd that was advancing towards them. Our artillery responded to that with shells and mortars," a spokesman for the British military in Qatar, Al Lockwood, was quoted as saying on Sky TV.

"We are carefully assessing the situation at the moment and certainly I'm sure that some action will be forthcoming in the morning," he added.

Iraqi Information Minister Mohammed al-Sahhaf has denied the reports.

"The situation is stable. Resistance is continuing and we are teaching them more lessons," the Qatar-based al-Jazeera TV quoted him as saying.

There was a revolt in Basra after the 1991 Gulf War. But without backup from the US-led forces, it was suppressed.

In Kuwait City, a British military spokesman, Colonel Chris Vernon, said British forces launched a "battle group operation" into Al-Zubayr near Basra, where they raided a Ba'ath party headquarters, seized a party politician, killed about 20 activists, and withdrew.

He said it is not surprising that the Iraqi army is withdrawing into cities and trying to draw the British and American forces there, because in a fight on an open ground they would be "seriously routed".

But he said the coalition forces would not fall for these tactics. Instead, they will try to draw the Iraqi armour and infantry to the outskirts and hit them there. "When we think the military situation is right, we will act," he said.

Col Vernon said they are trying to drive a wedge between the Ba'ath party and the people by gaining the confidence of the latter.

He also said there was a battalion-size counterattack from the southeastern side of Basra with about 20 vehicles, including tanks, making a dash for Al-Faw. But the attack was repulsed.

Meanwhile, the sandstorm has slowed down the progress of US troops towards Baghdad.

BBC quoted its correspondents as saying that visibility is just a few metres.

But despite the inclement weather, American B-2 bombers have carried out sorties. The target of the bombs is the Medina of the Republican Guards.

At the Pentagon, President George W Bush, said, "We cannot know the duration of this war, yet we know its outcome; we will prevail. The Iraqi regime will be disarmed; the Iraqi regime will be ended; the Iraqi people will be free and the world will be more secure and peaceful."

He had gone there to announce a budget request for a wartime supplementary of $74.7 billion.

"America has more than 200,000 people engaged in Operation Iraqi Freedom. They also continue to fight bravely on other fronts in this war on terror. Last week, coalition forces launched an operation against terrorists and their allies in the southern mountains of Afghanistan," he said.

In other developments

• Two British soldiers were killed when their Challenger II tank came under "friendly fire" outside Basra early on Tuesday, according to BBC.
• In another "friendly fire", an American F-16 fired on a US Patriot missile battery in Iraq, CNN said. The incident took place after the battery's radar locked on the jet, it quoted the US Central Command as saying. No casualties were reported.
• British Prime Minister Tony Blair on Tuesday said that the war against Iraq is proceeding "exactly as we thought it would". "Within five days of the conflict beginning, we are 100km south of Baghdad; a large part of Iraq has been secured and each of the main strategic objectives has been achieved," he said at his monthly news conference in London.
• A division of Halliburton Co, which was run by Vice-President Dick Cheney between 1995 and 2000, has got the main Iraqi oil well firefighting contract, the Pentagon said.
• The International Red Cross has restored 40 per cent of Basra's water supply, CNN quoted a US official as saying.
• Saudi Arabia has offered a peace proposal. But, according to CNN, a state department official said, "We're looking for elimination of this regime."