Taliban militants overran a district in southern Afghanistan and are pushing for control of another key area, sparking fierce clashes with NATO and Afghan forces that have left more than 100 people dead over three days, officials said Tuesday.

Hundreds of Taliban fighters launched raids on police posts near the strategic town of Chora in Uruzgan province Saturday, forcing NATO, backed by fighter jets, to respond. Fighting was continuing Tuesday, and some officials reported there have been dozens of civilian casualties.

Late Monday, Taliban occupied Miya Nishin district in neighboring Kandahar province, said provincial police chief Esmatullah Alizai. Authorities were planning an operation to retake the remote area, he said.

The insurgent push in the south appears to be the biggest Taliban offensive of the year and marks a change in tactics.

Until now, militants have relied largely on suicide and roadside bombings this year as NATO forces have escalated their operations to root them out. Violence has swelled, claiming about 2,400 lives during 2007, according to an Associated Press tally of figures from Western military and Afghan officials.

Maj. Gen. Jouke Eikelboom, director of operations with the Dutch military, which makes up most of the NATO forces in Uruzgan, said Monday that President Hamid Karzai and the provincial governor sought military support after the attack on the police posts.

"It has been a contested area for some number of months," NATO spokesman Maj. John Thomas said Tuesday. "(The Taliban) are making an effort right now to establish control in that area," he said, predicting more fighting in coming days.

Thomas said he could not pin down the number of fighters that NATO troops were up against but that the battle was not over. "There's reason to believe that the situation on the ground is still unstable," he said.

Precise casualty figures were not available because of the continued fighting, though two Afghan officials said more than 100 people have been killed, including at least 16 police. A Dutch soldier also died, and three others were wounded.

A summary of fighter jet activity from Sunday sent out by the U.S. Central Command hinted at the ferocity of the battles, detailing at least eight aircraft dropping bombs or firing on the area.

Afghan officials said Taliban fighters sought shelter in civilian homes and that NATO bombers targeted them.

One wounded man, Janu Akha, at the main Uruzgan hospital told The Associated Press that 18 members of his family had been killed.

Mullah Ahmidullah Khan, the head of Uruzgan's provincial council, estimated the clashes in Chora killed 60 civilians, 70 suspected Taliban militants and 16 Afghan police.

"I have talked to President Karzai and asked him to send helicopters to ferry the wounded to Kabul," he said.

An official close to the governor who asked not to be identified when talking about preliminary estimates, said 70 to 75 civilians were killed or wounded, while more than 100 Taliban and more than 35 police were killed.

Thomas said he doubted that Afghan officials could tell the difference between civilians and militants, suggesting some of the wounded who claimed to be civilians were insurgents.

The death toll in fighting in the south through Monday was part of a spike in violence over the last several days that has led to a mounting number of civilian casualties that are sapping support for foreign troops and Karzai's government.

Even though most civilian deaths are caused by attacks initiated by the Taliban, Afghan anger over civilian casualties is often directed toward U.S. and NATO-led troops. Such killings have prompted Afghan authorities to plead repeatedly for international forces to work more closely with Afghans.

On Tuesday, a group representing 94 foreign and Afghan aid agencies said that international and Afghan forces have been responsible for the deaths of at least 230 civilians so far this year, including 60 women and children.

"Initial goodwill towards the international military presence in 2002 has substantially diminished in many parts of the country," the Agency Coordinating Body for Afghan Relief said in a statement. "Excessive use of force and abusive raids and searches are undermining support not just for foreign and Afghan militaries but those involved in humanitarian and development work."

The Interior Ministry, meanwhile, announced that Karzai has approved a reshuffle and new appointments of police chiefs "to improve and maintain security" in six insurgency-wracked provinces: Helmand, Kandahar, Paktia, Zabul, Farah and Nuristan.

In other violence:

— Afghan troops killed seven suspected militants in Sangin district of Helmand province on Monday, the Defense Ministry said.

— Foreign troops raided a housing complex in Kandahar late Monday, killing one man and detaining ten others, witnesses and relatives said, although U.S.-led coalition and NATO said they have no reports of such an incident.