Suspected suicide attackers launched an assault near a base used by NATO-led forces in the western Afghan province of Herat on Thursday, authorities said, and gunfire was still being heard although there was no immediate word on casualties.

Herat government spokesman Mahuddin Noori said suicide bombers and gunmen had entered a separate compound used by a security firm near the NATO base and that fighting was continuing.

A spokesman for the NATO-led International Security Assistance Force (ISAF) said the explosion was about one kilometre from their Herat base. Italian troops are mainly based in Herat.

There has been an explosion outside the compound, the ISAF spokesman said.

He said there were no details about possible casualties.

The Herat attack was the latest in a string of assaults across Afghanistan.

On Saturday, a suicide car bomber killed 13 ISAF troops and civilian employees, as well as four Afghans, in Kabul, the deadliest single ground attack against the coalition since the war began 10 years ago.

Another three Afghan civilians were killed in a suicide attack in the southern Afghan city of Kandahar on Monday, officials said.

(Reporting by Sharafuddin Sharfyar, Jan Harvey and Mirwais Harooni; Writing by Christine Kearney; Editing by Paul Tait)