A senior Army officer says the Taleban's fightback against British troops in Afghanistan may be "more virulent" than expected.
Troops are having to deal with more Taleban resistance than expected
But Maj Gen Peter Wall insisted that British forces were "more than equal" to the challenge.
He said: "Every time we have met the Taleban in the last few weeks, we've endured, we've prevailed over them."
His comments come after two British soldiers were killed on Tuesday in attacks in the Helmand province.
Maj Gen Wall, deputy chief of joint operations, told BBC Radio 4's Today programme on Wednesday: "It's anticipated that as we roll out our force, the Taleban are going to challenge us.
"It's certainly so that yesterday we had a bad day - two brave men were killed in action - but I think the Taleban had a worse day."
'Violence and intimidation'
He also said Taleban forces did not have much to offer the Afghan population.
"The Taleban has very little to offer the people of southern Afghanistan other than violence and intimidation.
"And they are bound to challenge what we are trying to do in support of the Government of Afghanistan, which is to deliver security sufficient to roll out the development programme.
"So it would be optimistic not to expect them not to challenge us as we roll out our forces."
Maj Gen Wall said British forces in southern Afghanistan would become "fully-fledged" in the past few days, working alongside the Afghan national army.
"Notwithstanding yesterday's tragic losses, the force that we have has demonstrated it is more than equal to the task," he said.
"I don't accept we are involved in mission-creep; I do think that we should have expected a reaction from the Taleban.
"Perhaps it has been a little bit more virulent than we had hoped."
Rice visits Afghanistan
The two British soldiers who were killed were on night patrol in Sangin, in the volatile southern province of Helmand, when they were attacked by Taleban militia.
Another soldier was left seriously hurt but the Ministry of Defence said his injuries were not life-threatening.
The company of troops arrived in Sangin last week after about 40 members of the Afghan security forces had been killed in heavy fighting.
US Secretary of State Condoleezza Rice arrived in Afghanistan on Wednesday for talks with President Hamid Karzai amid rising security concerns in the country.
The past month has been one of the bloodiest in Afghanistan since the US-led invasion in 2001 and attacks blamed on the Taleban and their allies have increased in recent months.
In the past year more than 30 foreign soldiers have been killed, most of them Americans.
The number of UK soldiers in Afghanistan is expected to peak at 5,700 later this year - the majority of whom will be in Helmand.
They are heading a Nato mission charged with reconstructing the region following years of Taleban rule and a US-led invasion.
Information from the MoD shows that 10 British servicemen have died in Afghanistan since November 2001.