Insurgents wearing U.S. army uniforms launched pre-dawn attacks Saturday on a major NATO base in eastern Afghanistan and a nearby camp where seven CIA employees were killed last December in a suicide bombing.

NATO said there were no coalition casualties and the attacks were repelled.

The assaults on the Forward Operating Base Salerno and nearby Camp Chapman began around 3 a.m. local time, just as area residents were rising for morning prayers.

Afghan and coalition soldiers joined forces to repel about 50 insurgents. NATO officials said 21 insurgents were killed and five were captured during the co-ordinated attacks in Khost province, southeast of Kabul.

Afghanistan's Defence Ministry said two Afghan soldiers were killed and three wounded.

The insurgents used small-arms fire, rifles, heavy machine-guns and rocket-propelled grenades. Four who were wearing explosive vests were among the dead, officials said.

International Security Assistance Force spokesman Maj. Michael Johnson said the fighting took place in an area where insurgent attacks are becoming more common.

"We fully expect to receive more pressure from them because we are now operating in areas that they have had as safe areas for a long time. So we have gone out to the Taliban. We are on their ground in considerable numbers and we are making them very uncomfortable," he said.

NATO said the dead insurgents were members of the Haqqani Network, a Taliban-affiliated group with deep ties to al-Qaeda that is accused of launching frequent raids across the border from neighbouring Pakistan.

With files from The Associated Press