Troops are due to push into south-west Marjah in the coming days
Taliban militants battling coalition troops in Marjah, Afghanistan, are running out of ammunition, Nato officials say.
A BBC correspondent in Kandahar says that from eavesdropping on Taliban communications, Nato understands militants have called for support.
On Wednesday, an Afghan general said Taliban fighters were increasingly using civilians as "human shields".
The Afghan-Nato offensive in Helmand province is now in its sixth day.
Operation Moshtarak, meaning "together" in the Dari language, is the biggest coalition offensive since the Taliban fell in 2001.
Nato officers told BBC security correspondent Frank Gardner in Kandahar that the resistance they were currently encountering was coming from small, disjointed but determined groups of fighters.
In the next few days, US Marines and Afghan government troops are due to push into south-west Marjah, which is believed to be an insurgent stronghold.
But the head of the council for tribal elders in Helmand told BBC Pashto that the long-term security of the area depended on locals being involved in policing.
"As long as you don't get local people involved in the security, you will not be able to protect this area," Haji Abdurahman Sabir said.
"If police were from local people I am sure Marjah would have fallen within two days," he said.
He added that the people of Helmand felt isolated from Afghanistan's central government.
During fighting on Wednesday, US Marines had to call in air support as they came under heavy fire from fighters hiding in bunkers and in buildings including homes and mosques.
Afghan commander Gen Mohiudin Ghori said his soldiers had seen Taliban fighters placing women and children on the roofs of buildings and firing from behind them.
He told the AP news agency: "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."
Nato has stressed the safety of civilians in the areas targeted during Operation Moshtarak is its highest priority.
One villager who had fled to Helmand's provincial capital, Lashkar Gah, told BBC Pashto that relatives could not leave Marjah because the area was heavily mined.
"They say they can't get out of their home. If anyone takes a look outside they are fired upon by the Nato troops - they have no food left and can't go out to shop.
"The Taliban left some places but are now resisting very strongly."
On Wednesday, Helmand's governor, Gulab Mangal, visited Marjah and later travelled to Camp Bastion to visit injured civilians from the area.
A number of Afghan civilians remain in Marjah
Nato reports that he held a shura - a council meeting - with local tribal elders and officials to discuss security in Nad Ali.
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.
Afghan officials say that more than 1,200 families have been displaced and evacuated from Marjah and all are receiving aid in Lashkar Gah.
Meanwhile, it has been confirmed that three days of previously undisclosed talks took place last month between Afghan parliamentarians and Taliban representatives.
The Afghan and Maldives governments said the meeting took place in the Maldives but were not brokered by local officials or any other third party.