New Afghan war commander David Petraeus vowed yesterday to give his forces the right firepower to fight the Taliban amid a surging death toll but insisted sparing civilians remained a priority.

Commander Petraeus visited Nato headquarters in Brussels to brief allies before taking up his post in Afghanistan, where a new bout of fighting left at least 31 Taliban insurgents dead in the southern province of Helmand.

The US general admitted that troops were unhappy with the rules of engagement, which limit air strikes and artillery and mortar fire to prevent civilian casualties, but he denied that he planned to change them.

"There are concerns among the ranks of some of our troops on the ground that some of the processes have become a bit too bureaucratic," he told a news conference after meeting with Nato ambassadors.

"I have a moral imperative as a commander... to bring all force that is available to bear when our troopers, and by the way our Afghan partners, are in a tough position," Commander Petraeus said.

But the commander said there was "no intent to change" the rules, which are part of a troop surge strategy launched by the United States in a bid to beat back a resurgent Taliban insurgency.

"In a counter-insurgency the human terrain is the decisive terrain and therefore you must do everything humanly possible to protect the population and indeed again to reduce the loss of innocent civilian life," he said.

He said there had been a 50 per cent reduction in the loss of civilian lives in the last 12 weeks compared to the same period last year.

The rules were imposed by his predecessor, General Stanley McChrystal, who was fired by US President Barack Obama for disparaging remarks he made about administration officials in a magazine article.

Commander Petraeus visited Brussels just one day after the US Senate unanimously confirmed him as new war commander, with lawmakers hoping the man credited in Washington with turning around the Iraq war could do the same in Afghanistan.

Nato Secretary General Anders Fogh Rasmussen said the transatlantic alliance supported Commander Petraeus and the military strategy.

"The strategy has our full support," General Rasmussen said at the news conference. "This has been a change of command but it's not a change of strategy."

He added: "General, you are the right man to carry our mission forward."

Commander Petraeus, who was due to arrive in Kabul within days, takes over amid a tough fight that left more than 100 foreign troops dead in June, the deadliest month since the war began in the wake of the attacks of September 11, 2001 in the United States.

Nato also announced its first death in July. So far this year 323 troops have been killed, compared to 520 for all of 2009, according to an AFP count based on the independent icasualties.org website.

Meanwhile Nato forces in Afghanistan said yesterday they had killed at least 31 Taliban fighters and captured a rebel chieftain after a raid on an insurgent hideout in the southern province of Helmand.

Troops called in air support during running gunbattles in the province's troubled Baghran district which erupted after rebels attacked soldiers moving in on the compound with machine guns and rockets, it said.

Nato's International Security Assistance Force (ISAF) said in a statement that the Taliban chief of Naw Zad, another restive district of Helmand, was injured and detained following the fighting.

"Afghan and international security forces captured the Taliban district chief of Naw Zad and killed a large number of insurgents during an operation in remote Baghran district in northern Helmand province last night," it said.

German army General Josef Blotz, a spokesman for ISAF, said at least 31 insurgents had been killed in the operation.

"Throughout the four-hour firefight enemy forces attempted to use improvised explosive devices against the security force," he told reporters, referring to home-made bombs regularly used by the Taliban.

"However Afghan and coalition forces employed precision air fire and suppressed the enemy," adding that a huge arms cache and a quantity of opium had been discovered and destroyed.

Troops captured several wounded insurgents following the fighting, ISAF's statement said, and no civilian or soldier was hurt.