The top US and NATO commander in Afghanistan, David Petraeus, has issued new directives to his troops, stressing the need to avoid civilian casualties.

The order reiterates a lot of the rules of Gen Petraeus's predecessor, Gen Stanley MchChrystal.

Gen Petraeus took over as commander of the 140,000 US and NATO troops on 4 July.

President Barack Obama fired Gen McChrystal after a Rolling Stone interview was published which included some controversial comments.

"We must continue - indeed redouble - our efforts to reduce the loss of innocent civilian life to an absolute minimum. Every Afghan civilian death diminishes our cause," Gen Petraeus said.

The directive says, "If we use excessive force or operate contrary to our counter-insurgency principles, tactical victories may prove to be strategic setbacks."

The statement, released by the ISAF (International Security Assistance Force), claims that this does not prevent troops from protecting themselves or each other in self-defense.

Details, such as the conditions when troops are allowed to proceed with strikes without being able to assess civilian presence, were kept out of the public version for security reasons.

Gen McChrystal released a new order in 2009, limiting the circumstances in which troops could call in an air strike or open fire into buldings.

The US claims to have been effective at reducing the number of civilian deaths.

Some military officials raised concern that the emphasis on civilians put the lives of troops at risk.

There was some speculation as to thinking that Gen Petraeus woulds scale back the restrictions.

The new orders underlines the need to co-operation with Afghan forces, claiming that every patrol and operation must be with an Afghan unit.

"Some civilian casualties result from a misunderstanding or ignorance of local customs and behaviours," it states.

Last month, whistle-blowing website Wikileaks leaked a cache of documents relating to the Afghan war which suggested that many civilian casualties were going unreported.