Taliban fighters, including at least three suicide bombers, have attacked government buildings in the eastern city of Khost.

Security forces are engaging the attackers and a gun battle is still raging, the Afghan defence ministry said on Saturday.

General Mohammed Zahir Azimi, a spokesman for the defence minister, said that Afghan forces had surrounded the attackers and were firing on them.

A candidate in Afghanistan's upcoming presidential election was in one of the buildings at the time of the attack, but escaped unharmed.

Ramazan Bashardost, a former planning minister and one of 41 candidates in the presidential race, said later that he was not the target of the attack.

A Taliban spokesman confirmed to Al Jazeera that Bashardost had not been expressly targeted.

An Afghan official said the main targets appeared to be the police headquarters, attorney general's office, courts and a local bank branch.

The attack on Khost comes days after a similarly brazen assault by Taliban fighters and suicide bombers, some dressed as women, on the eastern city of Gardez in which nine people were killed.

Afghanistan has scheduled elections for August 20, but with growing violence across the large parts of the country and Afghan and international forces seemingly unable to ensure security, there are fears that few voters will turn out.