At least 18 people, including one American soldier were killed in a fresh bomb attack at Bagram air base in Afghanistan, where Dick Cheney, the US vice president, is visiting, officials said.

The attack occurred inside one of the security gates surrounding the heavily guarded base 60km north of Kabul.

Kabir Ahmad, Bagram district governor, said: "It was a suicide bombing. It took place between the main gate and the gate guarded by American soldiers.

Zemarai Bashary, an interior ministry spokesman, said: "Reports are stating that 18 people were killed and three of them are foreign soldiers.

"The 15 others are civilian Afghan workers who wanted to enter Bagram air base for their work. On injuries we do not have exact reports."

US military officials confirmed what they called a "direct attack" on the base.

A spokeswoman for Cheney said the vice president was safe.

Senior Master Sergeant Richard Simonsen in the Bagram media office told Agence France-Presse: "We have reports of one US soldier having been killed."

Cheney stayed at the base overnight after planned talks with Hamid Karzai, Afghanistan's president, were delayed by weather.

Later on Tuesday, the vice president arrived in Kabul to meet Karzai.

Major William Mitchell said it did not appear the explosion was intended as a threat to the vice president, who was "safely inside the base" during the blast.

PHOTO CAPTION

US Chinook helicopter taking off from Bagram air base 50-kms north of Kabul, in 2006. At least 21 people have been killed and 25 wounded in a string of attacks across Iraq, even as Iraqi and US troops intensified an operation to overrun insurgent hotbeds in the capital Baghdad. (AFP)