British troops take over Taliban stronghold

British forces officially took over the volatile Taliban stronghold of Helmand yesterday for what their commander admitted would be a "challenging mission".

The Stars and Stripes was lowered and the Union flag raised alongside the Afghan flag on a day of continuing violence in southern Afghanistan in which two civilians were killed and at least three foreign soldiers were injured in two suicide attacks and a roadside bombing. Canadian and Afghan forces claimed as many as 20 militants had been killed in fighting over the weekend.

Over the next few weeks thousands of British troops will deploy to the region - one of the most dangerous in the country, but the exact nature of their role remains mired in controversy.

The British, who are taking command of Helmand's provincial reconstruction team, have been keen to stress that they are not there as part of the American-led war on terror or to eradicate the opium crop. But John Reid, the Defence Secretary, acknowledged last week that they may have to launch offensive operations, including pre-emptive strikes against insurgents during a "complex and dangerous" mission.

Taliban fighters have already declared they plan to target British troops, labelling them an "old enemy of Afghanistan".

Two thousand British troops are already in Afghanistan with the number due to rise to 5,700 over the coming months. The Army's 3,300-strong deployment to Helmand, led by 16 Air Assault Brigade, will be completed by July and based in the provincial capital, Lashkar Gah, where two British soldiers were very seriously injured by a suicide bomber last month.

Brigadier Ed Butler, the commander of British forces in Afghanistan, denied there were any plans to tackle insurgency with pre-emptive strikes. "We are not going out to look for trouble," he said. "We have a window of opportunity where we can make a difference. We need to deliver our pledges."

He acknowledged that troops faced a "diverse and complex" challenge in a "less benign" area than the British had dealt with before, but he added: "Most importantly, we are starting to understand the nature of the problem and the violence is not about the insurgency, it's not about the Taliban or al-Qai'da. It's more fundamental than that. It's about tribal issues, it's about water and land rights, it's about feudal and historical matters, and that's what we need to understand," he added.

Brigadier Butler conceded that troops would be in Afghanistan for "a long time". "The UK has made a long-term commitment, as has the military, and we know it's going to take time to make a difference."

A suicide attacker detonated a device yesterday near an Afghan army convoy in the Greiskh district of Helmand but there were no reports of casualties other than the bomber.

There were two more attacks in the neighbouring provinces of Uruzgan and Kandahar. A suicide attacker in a car exploded a bomb near a convoy in Tirin Kot, the main town in Uruzgan, said provincial police chief Rozi Khan. One American soldier was injured and two civilians were killed.

Another bomb exploded near a Canadian-led convoy travelling in the Maiwand district of southern Kandahar province, injuring two soldiers and destroying their vehicle. In Khost, a suicide bomber was reported to have died when his device detonated prematurely, injuring an accomplice.

On Saturday a Canadian patrol attacked militants said to be carrying assault rifles and grenade launchers, who were "moving with the intent to set up an ambush" in the Sangin district of Helmand province, a military statement said. Between 15 and 20 were killed in the fight near the British base, Camp Bastion.

The Afghan army said it had killed four suspected Taliban militants and arrested a third on Sunday after a two-hour gun battle in the Chora district of Uruzgan province.