A bomb struck a bus taking Afghan soldiers to work in the capital Kabul early Thursday, killing the driver and wounding 25 more people, police and the defence ministry said.

The bomb, which the Taliban said they planted, was hidden in a car parked at the side of the road and was remotely detonated as the bus went by, an army officer said.

"Twenty-five wounded were taken to hospital," defence ministry spokesman General Mohammad Zahir Azimi told AFP. "22 are members of the defence ministry. There are three civilians. One person has died."

The city's criminal investigation chief Alishah Paktiawal said earlier the dead person was the driver of the bus. "It was a roadside bomb targeting an ANA (Afghan National Army) bus," he said.

He blamed the attack, one of a handful inside the city this year, on the "enemies of peace and stability in Afghanistan" -- a term Afghan officials often use and one generally understood to refer to Taliban insurgents.

Taliban spokesman Zabihullah Mujahid said later the extremist movement had carried out the attack.

The blast blew away one side of the bus and shattered its windows. Other vehicles in the area were damaged.

One of the passengers, Mohammad Hassan, said he had jumped out of one of the broken windows and helped to lift out the wounded.

"We were on our way to work. Suddenly I saw a big flame which rushed into the bus and I heard a big bang. I later realised it was a roadside bomb targeting our bus," the visibly shaken soldier told AFP.

"The bus drove into a wall and I jumped out of the window," he said. Hassan's beard and hair were singed and he had scratches on his ears, neck and face.

The Taliban-led insurgency that is gripping much of Afghanistan rarely penetrates the heavily secured capital, but the city has suffered several attacks.

Late Wednesday a senator who was prime minister for a few weeks in 1992, during the chaos of the civil war, was assassinated outside his home by unknown gunmen.

Abdul Sabur Farid Kuhestani, aged in his mid-fifties, was shot dead in an ambush, Paktiawal said. The motive was not clear.

In January this year another parliamentarian, Mawlawi Islam Mohammadi, was shot dead as he left his house in Kabul to walk to a local mosque.

On March 19 a suicide car bomb struck a US embassy convoy in the city, wounding five embassy guards and staff, one of whom died later.

Kabul saw relatively little of the insurgency until September last year when around seven bombings in little more than a month killed nearly 40 people including five foreign soldiers.

Some of the attacks were blamed on the Taliban but analysts said other disaffected groups against the Western-backed government could have also been involved.

PHOTO CAPTION

Afghan President Hamid Karzai addresses a press conference at the Presidential palace in Kabul. (AFP)