Forty militants and four soldiers were killed Monday when Pakistan troops clashed with dozens of militants, who went on the attack near a security post in the Shirin Darra area of Orakzai tribal district.

The rebels used rocket-propelled grenades to attack the post, killing four soldiers.

When troops reacted, the militant positions around Shirin Dara were peppered with bombs from jet fighters which were called in.

Around 35 rebels were killed in the fighting, according to Pakistan military officials.

Both sides are reported to still be exchanging sporadic gun-fire.

Pakistani forces have been battling the Taliban in the Orakzai district, after launching a major campaign in late March.

Orakzai borders the neighbouring district of South Waziristan, which has seen many clashes betwwen soldiers and rebels.