A suicide bomber rammed a water tanker into a Pakistani check post late Saturday, killing 17 soldiers in the notorious tribal district of North Waziristan.

A suicide bomber rammed a water tanker into a Pakistani check post late Saturday, killing 17 soldiers in the notorious tribal district of North Waziristan, the military said.

There was no immediate claim of responsibility for the attack. North Waziristan is perhaps the most notorious of Pakistan's tribal districts on the Afghan border, a known stronghold of the Taliban and Al-Qaeda-linked operatives.

The deaths were a reminder of the serious security threat in Pakistan, just hours before former military ruler Pervez Musharraf was due to return home to the southern city of Karachi to contest historic general elections after more than four years in exile.

Security officials explained the sudden increase in the death toll after it jumped from six by saying that many of the dead had been trapped under the rubble following the blast.

Another 10 soldiers were also wounded in the attack on a check post operated jointly by the regular army and the Frontier Corps paramilitary.

Musharraf Saturday told Der Spiegel he wanted to free his homeland from terrorism when he returned.

"I want to put Pakistan on the road to prosperity and free it from terrorism," he said in the interview with the German magazine.

As ruler of Pakistan, he escaped three Al-Qaeda assassination attempts. He became a prominent target for extremists after becoming a key US ally in the "war on terror" after the 9/11 attacks.

Pakistani troops have fought for years against homegrown insurgents in the tribal belt on the Afghan border.

There are fears that insecurity could prove a major challenge for historic general elections on May 11, which should mark the first democratic transition of power between two civilian governments in Pakistani history.