WASHINGTON: Nato has issued orders to restrict air strikes on insurgents hiding in residential homes in Afghanistan after an allied raid that left up to 18 civilians dead, a top US general said Monday.

The head of the coalition force, General John Allen, handed down “guidance that we will not employ aerial-delivered munitions on a civilian dwelling, unless, of course, it is the last resort, and it is, in fact, to ensure the defense of our soldiers,” Lieutenant General Curtis Scaparrotti, deputy commander of US forces, told reporters via video link from Kabul.

“It does not mean that we will not go after insurgents, that we don't expect insurgents ...to use civilian dwellings,” he said.

His comments followed a statement from Afghan President Hamid Karzai on Saturday that said the Nato commander had “promised” a halt to air strikes on residential areas.

General Allen took the extraordinary step of flying to Logar province, south of Kabul, to apologize over the deaths of civilians in an air raid conducted early Wednesday.

Nato says the air strike targeted insurgents in a residential home but Afghan officials say 18 civilians died in the attack.

Despite the incident, the Nato-led International Security Assistance Force (Isaf) has made progress in recent months in reducing the number of civilians casualties from its operations, according to Scaparrotti.

He said that air strikes against insurgents sheltering in civilian homes made up a small fraction of overall coalition air attacks.

Out of a total of 3,531 Nato air strikes in the past six months, only 19 civilian compounds were targeted and of those, five resulted in civilian casualties, he said.

“It's a very small number that actually are in (civilian) compounds,” he said.

The rules for employing air strikes have shifted back and forth during the ten-year-old war.

In 2009, then-commander General Stanley McChrystal ordered limits on fire power from aircraft and artillery, warning that civilian casualties risked undermining Nato’s effort and alienating the Afghan population.

But when former General David Petraeus took over in 2010, he eased some rules amid complaints that troops had been placed in a dangerous position and denied back-up from warplanes and attack helicopters.

Scaparrotti said the new guidance would not prevent coalition troops from defending themselves.

He said that “if they’re in a situation where there are no other options, of course they'll have availability of air-delivered munitions.”Pentagon spokesman George Little said the new orders would not take the pressure off of the Taliban insurgency.

“This should not be taken by the insurgents as any sign that they will be somehow safer or more protected because of this decision,” he told reporters.