Taliban militants are increasingly using civilians as "human shields" as they battle against a joint Afghan-Nato offensive, an Afghan general has said.
Gen Mohiudin Ghori said his soldiers had seen Taliban fighters placing women and children on the roofs of buildings and firing from behind them.
The joint offensive in southern Helmand province has entered its fifth day.
US Marines fighting to take the Taliban haven of Marjah have had to call in air support as they come under heavy fire.
They have faced sustained machine-gun fire from fighters hiding in bunkers and in buildings including homes and mosques.
They are trying to get us to fire on them and kill the civilians
Gen Ghori, the senior commander for Afghan troops in the area, accused the Taliban of taking civilians hostage in Marjah and putting them in the line of fire.
"Especially in the south of Marjah, the enemy is fighting from compounds where soldiers can very clearly see women or children on the roof or in a second-floor or third-floor window," he is quoted by Associated Press as saying.
"They are trying to get us to fire on them and kill the civilians."
As a result, his forces were having to make the choice either not to return fire, he said, or to advance much more slowly in order to distinguish militants from civilians.
Nato has stressed that the safety of civilians in the areas targeted in the joint Nato and Afghan Operation Moshtarak is its highest priority.
Nato has said that safeguarding civilians is its top priority
Journalist Jawad Dawari, based in Lashkar Gah, told BBC Pashto that Taliban fighters remained in many residential areas of Marjah and were defending their positions with heavy weapons.
"It is difficult for the Afghan army and Nato to storm Taliban-held areas because to do so may inflict heavy civilian casualties and there are still a lot of civilians in Marjah.
"Whenever they launch an attack, the Taliban take refuge in civilians' homes."
He had spoken to many local people in Marjah, he said, and they had all said the Nato offensive had made little progress since the first day.
An Afghan military official had told reporters that the backbone of the resistance came from foreign fighters - Pakistani and Arab - and that it was feared they might resort to suicide attacks, he added.
Improvised bombs
As well as meeting pockets of stiff resistance, the troops taking part in the offensive have been having to deal with large numbers of improvised bombs, the BBC's Frank Gardner in Kandahar says.
American forces have found a so-called "daisy chain" - a long bomb rigged up from mortar bombs, rocket-propelled grenades and a motorbike, our correspondent says.
And British engineers have deployed a device called a "python" - a length of explosives designed to set off mines and clear a safe path through them, he says.
Afghan army chief of staff Besmillah Khan told the AFP news agency the threat from improvised bombs meant gains were coming "slowly".
Meanwhile, to the north, British forces have discovered an insurgent cache of stolen Afghan army and police uniforms.
The find suggests the Taliban could have been planning attacks disguised as Afghan security personnel, our correspondent says.
Nato says discussions with the local population on how to bring lasting security to the area are continuing, our correspondent adds.
British and Afghan troops are reported to be advancing more swiftly in the nearby district of Nad Ali than are their US and Afghan counterparts in Marjah.
Missiles 'on target'
The commander of British forces in southern Afghanistan said on Tuesday a missile that struck a house outside Marjah on Sunday killing 12 people, including six children, had hit its intended target.
Maj Gen Nick Carter said the rocket had not malfunctioned and the US system responsible for firing it was back in use. Officials say three Taliban, as well as civilians, were in the house.
Initial Nato reports said the missile had landed about 300m (984ft) off its intended target. Gen Carter blamed these "conflicting" reports on "the fog of war".
He said that protecting the local population remained at the heart of the operation.
Speaking on Tuesday, Dawud Ahmadi - a spokesman for Helmand Governor Gulab Mangal - said the Afghan National Army and Nato forces were clearing areas around Marjah of mines.
Mr Ahmadi said that 1,240 families had been displaced and evacuated from Marjah - and all had received aid in the provincial capital, Lashkar Gah.
Operation Moshtarak, meaning "together" in the Dari language, is the biggest coalition attack since the Taliban fell in 2001.
Allied officials have reported only two coalition deaths so far - one American and one Briton killed on Saturday.