A roadside bomb exploded Sunday killing a local government official and four policemen in Pakistan's restive northwestern tribal area bordering Afghanistan, officials said.

The blast took place in the town of Mamoond, some 25 kilometres (15 miles) from Khar, the main town of Bajaur, one of the country's seven semi-autonomous tribal districts, where the army has been battling Taliban militants.

"A local government officer and four tribal police were killed and another was wounded when an improvised explosive device planted on a roadside exploded when their vehicle passed," senior local government official Anwarul Haq told AFP.

Local security officials confirmed the attack and casualties.

The Pakistani Taliban group said it carried out an attack on Sunday that killed five people.

Tehreek-e-Taliban Pakistan (TTP) spokesman Mohammad Khurassani said the militants planted an improvised explosive device “to target security personnel” in the Bajaur Agency area that is part of the Federally Administered Tribal Areas (FATA).

Bajaur is one of the Pashtun tribal regions near the Afghan border. Security in the region has improved in recent years after the Pakistani military mounted offensives there against the al Qaeda-linked Pakistani Taliban, which is considered the country’s biggest security threat.

But militants continue to stage attacks in FATA, which remains off-bounds for foreigners and is considered one of the most volatile parts of the nuclear-armed nation of 208 million people.