Nato commanders called on the Taliban to surrender as troops dug in yesterday for a major assault on one of the last insurgent strongholds in southern Afghanistan, sending thousands of residents fleeing.

The Taliban remained defiant as civilians of the Marjah plain accused the militia, which is leading an eight-year insurgency, of massing fighters and arms for a bloody battle in Helmand province expected to start this week.

Taliban fighters "prefer to stay and fight," Yousuf Ahmadi, a purported Taliban spokesman, told AFP by telephone from an undisclosed location.

"Afghan and foreign forces have come to the Marjah area and our Mujahideen forces are also in the area firing rockets at them," he said.

Brigadier General Eric Tremblay, spokesman for Nato's International Security Assistance Force, called on the militants to lay down their arms, and said the aim of the operation was to "separate the insurgents from the population".

"From a strategic perspective it would be better but they are under very high instructions from their senior leadership to stay and fight, and they are still under the impression that they are winning," he said.

A stream of frightened families were packing up their belongings and leaving Marjah, as provincial authorities set up emergency reception centres and stockpiled food and tents for up to 10,000 people.

Helmand provincial officials held an emergency meeting to discuss the situation, as displaced people continued to descend on the provincial capital of Lashkar Gah and other towns.

Ghulam Farooq Noorzai, head of the provincial department of refugees and repatriation, said more than 400 families, or 2,000-3,000 people had relocated and "people are still leaving the area".

"We have provided some 70 tents with the help of the international military and in Lashkar Gah we have set aside two schools to shelter people as they arrive," he said.

Shir Ali Khan, who arrived Monday in Lashkar Gah with 25 relatives, said he would keep his loved ones in the city until Marjah was safe.