A top NATO general on Sunday said an offensive aimed at driving Taliban militants from some safe havens in southern Afghanistan has been "successfully completed," even as suicide bombers struck military convoys, wounding six soldiers.

As NATO lauded success in the south, militants that slipped away took control over a district in the west of the country after chasing away the police, an official said.

Lt. Gen. David Richards, head of the 20,000-strong NATO-led force in Afghanistan, said the insurgents have been forced out of the volatile former Taliban heartland, and reconstruction and development efforts there would soon begin.

CountryWatch: Afghanistan

Alliance officials have said more than 500 militants were killed during the two-week long operation, centered mainly in Panjwai, Pashmul and Zhari districts of southern Kandahar province.

Meanwhile, two foreign military convoys came under attack from suicide bombers Sunday, a method frequently used by insurgents in Iraq.

A 17-year-old youth carrying explosives jumped in front of a U.S. military convoy east of Kabul, killing a bystander and wounding three American soldiers, Afghan police said.

Earlier in the day, a suicide bomber plowed his explosive-laden vehicle into a Canadian military convoy in southern Afghanistan, killing one civilian and wounding three soldiers, the military said.

The attack west of Kandahar city also wounded eight civilians, said Zulmai Khan, a police official at the scene.

Most of Afghanistan's recent surge in violence has taken place in volatile southern provinces, where some 8,000 NATO forces took military control from the U.S.-led coalition on Aug. 1. NATO commanders say they need another 2,500 troops plus greater air support to crush the Taliban threat more quickly.

Richards said that the end of the southern offensive should open the way for much needed reconstruction and development in areas where the central government has been unable to reach.

But in an apparent attempt to open a new front, some 400 Taliban crossed into the western Farah province, taking control of its Gulistan district after chasing away the police there, said Gen. Sayed Aqa Saqib, the provincial police chief.

The militants firing rocket-propelled grenades and heavy machine-guns burnt the district headquarters and a local clinic, he said. There were no immediate reports of casualties.

"We are hoping government will send more troops, because there are too many Taliban in the area," Saqib told AP over the phone.

Gen. Sher Mohammad Karimi, the Afghan National Army's chief of operations, acknowledged that the Taliban "were not all destroyed" and that some have simply slipped away into other areas.

"They may reorganize but our troops will follow," Karimi said.

But Richards ruled out immediately pursuing the Taliban holdouts.

"We will not dance to the Taliban's tune," Richards said. "They want to deflect us and take us away. We won't let them do that."

The end of one operation coincided with a start of a new U.S. and Afghan offensive in the east of the country.

Dubbed Operation Mountain Fury, the new offensive involves 7,000 U.S. and Afghan soldiers in the central and eastern provinces of Paktika, Khost, Ghazni, Paktya and Logar, the military said. Fighter planes and helicopters will back the ground forces.

A separate U.S.-led operation called Big Northern Wind has been under way in Kunar province's Korangal Valley since late August.

Taliban and other Islamic extremist groups, including Al Qaeda, are known to operate in the east, especially in the area bordering Pakistan where the reach of the government is weak and militants find sanctuaries.

The renewed American push to defeat the Taliban-led insurgency comes nearly five years after the U.S.-led invasion ousted the hard-line militia from power.

Separately, the mutilated body of an Afghan engineer was found Sunday in Ghazni province, where he had been kidnapped earlier in the week by suspected Taliban militants, said Ali Ahmad Fakuri, the provincial governor's spokesman.

The victim had worked for a local aid agency involved in rural development, he said.