A Pakistani military official says Taliban fighters attacked an army post in the country's northwest near the Afghan border, killing nine soldiers.

The attack occurred on Wednesday in the South Waziristan tribal area, once the main stronghold for the Pakistani Taliban, and was a reminder of the threat posed by fighters despite numerous military offensives against them.

The Pakistani Taliban claimed responsibility for the attack. The group's spokesman, Ahsanullah Ahsan, said they killed 12 soldiers and beheaded some of them.

The differing accounts could not be independently verified.

The Pakistan military launched a large offensive against armed groups there in 2009, but they still operate in the area and periodically stage attacks.

In addition to the nine soldiers killed, several others were wounded in the attack on the post near Ghatbadr village in the Shakai Valley, the Pakistani military official said, speaking on condition of anonymity because he was not authorised to talk to the media.

The attack started just before midnight and lasted for several hours, he said.

The military has conducted offensives against the Pakistani Taliban in six of the seven areas that make up Pakistan's semi-autonomous tribal region along the Afghan border.

The US said recently that Pakistan plans to launch an operation against the Pakistani Taliban in the group's last major sanctuary in region, North Waziristan.

But Pakistani military officials have downplayed the comments, saying they plan to slowly increase pressure against fighters in North Waziristan rather than launch a sweeping offensive.

Many Pakistani Taliban fighters fled to North Waziristan and other parts of the tribal region following the army operation in South Waziristan in 2009.