Officials in southern Afghanistan say militants have killed at least three policemen during a gunbattle in the city of Kandahar.

The officials said the clash happened early Wednesday, and that the district police chief is among the dead.

The attack comes as Afghan forces continue to take security control of some areas from NATO troops, and international forces begin leaving the country.

U.S. forces handed over control of the relatively peaceful city of Mehterlam in eastern Laghman province during a ceremony on Tuesday.

The provincial capital is one of seven areas in Afghanistan to be transferred to the Afghan government this month. It is the first phase of a plan that will see all of the country's security under Afghan control in the next three years.

International combat troops are set to completely withdraw from Afghanistan by the end of 2014.

Security control of Lashgar Gah, the capital of southern Helmand province, is set to be handed over to local troops later this week.

Afghan officials said seven police officers were killed by one of their colleagues at a checkpoint outside the city Monday.

In violence Tuesday, NATO said two of its service members died in separate bomb blasts in eastern Afghanistan.

South of Kabul, police said two bomb blasts within minutes of each other killed two civilians and wounded at least nine others in Ghazni city.

Violence has increased in Afghanistan since President Hamid Karzai announced the first phase of the security transition.

Despite the violence, the Afghan government official who heads the transition process said Tuesday that Afghan forces were fully capable of handling security in the seven areas to be transitioned first.

On Sunday, Bamiyan province became the first area to be handed over to Afghan forces.