CAMP PENDLETON: The commanding Marine general in one of Afghanistan's hardest-fought regions said Friday he is seeing big improvements in the vetting of Afghan recruits to the country's security forces following attacks by Afghan soldiers on their Nato partners.

Maj. Gen. C. Mark Gurganus told reporters at Camp Pendleton in a teleconference call from Afghanistan that he believes Afghan forces will take the lead in securing Helmand Province by this fall - faster than expected.

Gurganus said Helmand's provincial chief of police told him May 19 that he has imposed new policies including enforcing an age limit of 18 for police recruits, barring police from bringing guests into their posts, and strictly holding commanders responsible for their officers' actions.

Gurganus, who took over command of the US Marines in Helmand Province in March, said soldiers who go on extended leave or travel to Pakistan are being prescreened.

''They are watching these guys a little more carefully,'' Gurganus said. ''They are taking some steps that are really huge in terms of their culture. They've really taken this to heart.''

There have been about 20 deadly attacks by Afghans in uniform on their Nato partners this year, including one May 6 that left one Marine dead and another wounded.

The shooting, in which the Afghan soldier was killed in return fire by coalition troops, marked the second recent killing of a US Marine in Helmand by an Afghan soldier.

The coalition does not report attacks in which an Afghan security force member wounds or misses his US or allied target.

Persistent violence and the insider attacks have undermined President Barack Obama's efforts to show progress in stabilizing Afghanistan. They also have raised the level of mistrust between the US-led coalition and its Afghan partners as Nato prepares to hand over the security reins to local forces ahead of a 2014 deadline for the withdrawal of combat troops.

Gurganus said some of the soldiers may have been ideologically opposed to coalition forces, others may have gone over to the other side after going home on leave, or their families may have been threatened by insurgents.

He said the Marine Corps has been reemphasizing its cultural training to try to curb incidents of troops offending their Afghan counterparts.

The general spoke the same day French President Francois Hollande defended his decision to pull the country's 2,000 combat troops out of Afghanistan two years early.

Former French President Nicolas Sarkozy announced the accelerated withdrawal after four French troops were killed by a rogue Afghan soldier in January.

A speedy withdrawal by others nations would destabilize the plan for Afghan forces to gradually take charge of the country's security over the next 2 1/2 years.

The Afghan army and police have started taking charge of security in areas that are home to 75 per cent of the population.

The goal is for Afghan forces to be in the lead across the country by mid-2013. Nato and other foreign forces would then assume a support role for the 352,000-strong Afghan security forces until the end of 2014.