A bomb has exploded near NATO's military headquarters in Kabul, in the second bombing of the day in Afghanistan.

The blast occurred on Saturday evening "in the vicinity" of Camp Eggers, a base belonging to NATO's ISAF force and located near the Afghan presidential palace and several embassies, a spokeswoman for ISAF told AP news agency.

No casualties were initially reported, and the cause of the explosion is under investigation, the spokeswoman said.

The explosion comes after six Taliban fighters launched an assault on a joint Afghan-NATO base in eastern Afghanistan's Nangarhar province on Saturday morning, killing a NATO soldier.

One attacker in an explosives-packed vehicle blew himself up at the entrance to the base, and five other fighters were shot as they tried to storm the facility.

NATO's International Security Assistance Force (ISAF) confirmed one fatality in a suicide attack in the east of the country, without giving further details.

Afghan and Western officials said the attack took place in Ghani Khil district, a volatile area on the main highway from Kabul to neighbouring Pakistan, where many Taliban fighters seek shelter.

"Around 8am, a suicide bomber detonated himself and the other five were gunned down by Afghan security forces. Their bodies lie at the scene," Ahmad Zia Abdulzai, spokesman for the Nangarhar governor, told AFP news agency.

In an emailed statement to the media, Taliban spokesman Zabihullah Mujahid claimed responsibility for the attack.

Nangarhar province has seen a deteriorating security situation in the past three years, which given its proximity to Kabul and the fact that Jalalabad is one of the five largest cities in the country could be dangerous.

Meanwhile, the Afghan president, Hamid Karzai, has delayed the prison release of 88 Taliban fighters after US complaints that the fighters might return to the battlefield, officials said on Saturday.

"Based on a recent president's order, we have started again reviewing the cases of the 88 prisoners," Abdul Shokur Dadras, a member of the Afghan Review Board, told AFP news agency.

US General Joseph Dunford, commander of NATO forces in Afghanistan, had lodged an official objection to the planned releases, saying they went against an agreement signed when Bagram prison was handed over to Afghan control last March.

The Afghan review board ordered the release of 648 Bagram prisoners last year, of which 560 have been freed so far.

This year will see the end of the US-led NATO combat mission in Afghanistan as 85,000 foreign troops pull out, though a long-delayed security deal could allow several thousand US soldiers to remain to train and advise local security forces.