BAGRAM, Feb 27: A suicide bomber attacked the entrance to the main US military base in Afghanistan on Tuesday during a visit by Vice-President Dick Cheney, killing 23 people and wounding another 20. The Taliban claimed responsibility and said Mr Cheney was the target.

The vice-president told reporters he heard `a loud boom’ and that the Secret Service informed him of the attack. Officials then moved him to a bomb shelter on Bagram.

“As the situation settled down and they had a better sense of what was going on, I went back to my room,” Mr Cheney said.

Asked if the Taliban were trying to send a message with the attack, Mr Cheney said that fighters `clearly try to find ways to question the authority of the central government’.

“Striking at the Bagram (base) with a suicide bomber, I suppose, is one way to do that,” he said. “It shouldn't affect our behaviour.”

The vice-president met President Hamid Karzai in Kabul two hours after the bombing.

Earlier, the US vice-president ate with soldiers, telling reporters that `breakfast was excellent’, but making no other comments.

The explosion happened at 10am near the first of three gated checkpoints vehicles must pass through before gaining access to Bagram. The sprawling base houses 5,100 US troops and 4,000 soldiers from other western countries.

High security areas within the base are blocked by their own checkpoints. It was unclear how an attacker could expect to penetrate the base, locate the vice-president and get close to him without detection.

“We maintain a high-level of security here at all times. Our security measures were in place and the killer never had access to the base,” said Lt Col James Bonner, the base operations commander. “When he realised he would not be able to get onto the base he attacked the local population.”

Eyewitnesses said they had seen bodies being carried in black bags and wooden coffins from the base entrance into a market area where hundreds of Afghans had gathered to mourn.

Major William Mitchell, another US army official, said it did not appear the explosion was intended as a threat to the vice-president. “He wasn't near the site of the explosion,” Major Mitchell said. “He was safely within the base at the time of the explosion.”

But a purported Taliban spokesman, Qari Yousef Ahmadi, said Mr Cheney was the target of the attack, which Ahmadi said was carried out by an Afghan, known as Mullah Abdul Rahim.

“We knew that Dick Cheney would be staying inside the base,” Ahmadi said. “The attacker was trying to reach Cheney.”

Maj Mitchell noted that Mr Cheney's overnight stay occurred only after a meeting with President Karzai on Monday was cancelled because of bad weather.“I think it’s a far-fetched allegation,” he said, referring to the Taliban claim. “The vice-president wasn’t even supposed to be here overnight, so this would have been a surprise to everybody.”

Mr Cheney, who spent the night at Bagram, left the base about two hours after the blast.

“The vice-president is fine” said his spokeswoman, Lea Anne McBride.

Cheney later flew by plane to Kabul to meet Mr Karzai.

South Korea's defence ministry said one of its troops was killed in the explosion.

In Kandahar, a suicide attacker targeting Afghan police blew himself up, wounding three people.

Nato-led troops also fatally shot a civilian who drove too close to their convoy.—AP