GARDEZ, Sept 16: Afghan President Hamid Karzai escaped an assassination bid on Thursday when a rocket was fired at his US military helicopter as it was landing here.

Just hours later, President Karzai said he was confident of winning next month's election and said foreign troops would stay in the country until it could take care for itself.

The most serious challenge yet to an Oct 9 presidential election, for which the Taliban claimed responsibility, came as President Karzai's rivals called for the vote to be delayed by at least a month, saying security worries made campaigning difficult.

"A rocket was fired at President Karzai as his helicopter was landing," US military spokesman Maj Mark McCann said. "It missed and landed about 300 metres from a school in the vicinity of the landing area."

The rocket flew over President Karzai's helicopter but caused no injuries, witnesses said. The president's campaign trip, his first outside Kabul, was immediately aborted and he was flown back to Kabul, the US military and Afghan officials said.

"The security is really over precautious," President Karzai said, adding he had wanted to land at Gardez to address the crowd. "We will have this (international) force till Afghanistan is firmly on its own feet with regard to its security forces, with regard to its police, with regard to its national army, with regard to its economy, with regard to its government...

"Only then can we ask the international security forces to leave - not till we are fully capable of defending ourselves against everybody else that may be trying to hurt us."

Taliban commander Mullah Abdur Rauf said the guerrillas learned of Karzai's trip on Wednesday and planned the attack. "Because of shortage of time, we could fire only one rocket. It was launched by remote control," he said.

Eight of President Karzai's 17 poll rivals, including his main challenger, former education minister Yunus Qanuni, said insufficient time had been allowed for the campaign, given the lack of security and logistical problems in the provinces. -Reuters