The commander of the British marines arriving to fight terrorists in Afghanistan has warned of the strain that their heavy schedule is placing on his men's families.

While he has no doubts over his troops' ability and willingness to do the job at hand, Lt Col Tim Chicken, commanding officer of 45 Commando, says there are consequences to the constant demands on his forces' time, and he hopes that once the operation was complete his men might be granted some quality time.

"A year ago we came back from Kosovo and reformed to a new organisation of battle, early July we did a UK-based exercise, then we went to Oman," he said.

"From mid-November to mid-December we did mountain training, then short notice embarkation, and then Afghanistan.

"The last time we had time to catch breath was a long time ago. We can do the job, but families and friends are the ones who bear the brunt."

He warned that the troops face a "wily, determined and committed foe who's going to be incredibly difficult to combat".

British military sources have stressed that the Taliban and al-Qaeda forces they face are far from beaten. They warn that a hiatus in Taliban and al-Qaeda activities is just an "operational pause", and that preparations for a new phase is under way.

Major Tony de Reya has said that this could include limited terrorist attacks, mine threats, snap ambushes, and drive-by shootings although garnering precise information is a "real intelligence challenge".

Nevertheless, Lt Col Chicken said he was confident of his troops' physical and technical preparedness for the task ahead, as well as their mental ability to cope with the human complexities. He said that 45 Commando's experience last year in Kosovo, has proved its ability to deal with foreign cultures.

That does not mean, however, that the road will be easy. "Dealing with Afghan forces will be particularly difficult. They are a culture away from us in military terms, although they bring an enormous benefit to us as well," he said.

"I'm not in any way apprehensive about it, but I'm conscious of the fact that I'm going to have to invest a degree of effort, and I'm going to have to ensure my boys get absolutely crystal direction as to how they handle that."

It is a heavy responsibility for the 42-year-old, who was appointed in December 2000, and can lead to moments of reflection. "You feel an odd sense as you fly over villages and wonder whether or not they're thinking about me," he said. "I wonder whether they're thinking 'I'm on their side', or not."

As the full deployment of 1,700 troops begins to filter in over the next two weeks, the marines are busy brushing up on basic skills, such as mine awareness, and familiarising themselves with new surveillance and radio equipment.

3 Commando Brigade is still expected to be operational by mid-April although "that does not mean that on the 15th we'll fix bayonets and start marching", according to Lt Col Paul Harradine, its spokesman.

Speaking after a brief trek through a nest of wrecked fuselages, tail fins and turbines near the British encampment - the detritus of decades of war - Adam Ingram, the British minister for the armed forces, stressed the importance of the operation.

"This is a very big task we've asked them to undertake," he said.

"I've said to them they will make a difference, not just in this country, but the way in which this will play beyond the boundaries of Afghanistan."

But to questions over how long the British forces will remain, Mr Ingram remained non-committal. "We'll be here until the job is done," he said.