Pakistani officials say troops have killed at least 25 militants in fighting near the border with Afghanistan.

A military spokesman, Major General Waheed Arshad, says the clashes began late Tuesday following the abduction of four Pakistani paramilitary soldiers in the South Waziristan region.

The soldiers had been moving on foot to their base in the tribal area, when they were overpowered and kidnapped by militants near the Afghan border.

Pakistani security forces launched artillery and mortar fire at militant positions in response.  No soldiers were killed in the fighting.

Pakistan's government had earlier blamed South Waziristan-based militant leader Baitullah Mehsud for the assassination of opposition leader Benazir Bhutto in Rawalpindi.

Mehsud has denied involvement in last week's attack on Bhutto.

Pakistani troops have been fighting intense battles with militants along the Afghan border.

Some information for this report was provided by AFP, AP and Reuters.