Black Watch soldiers were involved in the initial phase of the operation
British forces on a major operation in Afghanistan say they have encountered little resistance from the Taliban.
Troops are moving into a large swathe of territory in Helmand province that had been a stronghold for insurgents.
More than 700 British soldiers from the Light Dragoons and 2 Mercian are taking part in the third wave of Operation Panther's Claw.
They are trying to clear a large area of land of insurgents and install Afghan government rule.
The BBC's Ian Pannell, who is with the troops, says it is still very early days in this part of the operation but the resistance British commanders expected has not yet materialised.
Many residents have fled the area because of the fighting. Phase one of the operation involved clearing private compounds which had been used by the insurgents to launch attacks.
WITH THE TROOPS
By the BBC's Ian Pannell in Marja district, Helmand
How do you defeat the Taliban? After eight years, military commanders admit the battle has reached a stalemate and are trying something new.
In essence it is about winning over the population rather than just fighting the Taliban. The thinking is that of you control the main populated areas you will effectively drive the insurgents out.
Day one of this operation was searingly hot. We were woken by the sound of mortar shells being fired out of camp and dust as fine a flour being whipped up by a blistering wind.
Throughout the day hundreds of British troops have moved into place, crossing the canal into Marja district and starting to take over the small mud-built compounds strewn around the fields and orchards of the Green Zone. It has that name not for its colour or beauty but for its danger. More than 50 IEDs, or booby-trapped bombs, have been found in the last few days in this area alone.
On day one of this campaign a roadside bomb exploded under a British armoured vehicle. The soldiers were incredibly lucky this time, and they escaped with only minor injuries. But they know the battle for Helmand and its citizens is going to be long, slow, and some of them may not be coming home.
The biggest danger they face is from booby-trapped bombs which are often hidden in the surface of the road.
Our correspondent says there have already been UK fatalities in the operation and that commanders are braced for more to come.
The operation comes as US and Afghan forces met "heavy resistance" from Taliban fighters in the province.
The co-ordinated "surge" of soldiers aims to make the area safe ahead of presidential elections in August.
Operation Panther's Claw, which began a fortnight ago with an air assault on the region of Babaji, north of Lashkar Gah, had broadly the same objectives.
More than 350 troops from the Black Watch were dropped into the area backed by 12 Chinook helicopters in what the Ministry of Defence described as one of the largest air operations in modern times.
Two British soldiers taking part in the operation - Lt Col Rupert Thorneloe, commanding officer of the 1st Battalion Welsh Guards, and Trooper Joshua Hammond, of 2nd Royal Tank Regiment - were killed in an explosion in Helmand on Wednesday.
Lt Col Thorneloe was the highest ranking army officer to be killed in action since the Falklands War in 1982.
The latest phase of the offensive involves a major land assault, with soldiers backed up by artillery and air support.
The arrival of thousands of US marines to the area had freed up the Light Dragoons battle group to launch the offensive.
The assault has been co-ordinated with the ongoing US operation to the south - codenamed Khanjar, or Strike of the Sword.