Peshawar: A suicide bomb attack on a crowded festival and market in northwest Pakistan's northwest has killed at least 25 people and wounded 20, a government official says.

The blast occurred at around the same time that three attackers tried to storm the Chinese consulate in the southern city of Karachi. Two policemen and the three attackers were killed.

The Karachi attack was claimed by a separatist insurgent group called the Balochistan Liberation Army, and did not appear to be connected to the attack on the market in the northwestern region of Orakzai.

In Orakzai, a suicide bomber drove a motorcycle into a crowd attending a festival and market that attracts people from different religious communities, before detonating his explosives.

No group claimed responsibility.

"It was a suicide blast at the festival that takes place every Friday," said Abbas Khan, the assistant commissioner of the district, told Reuters.

Khan said that among the 25 dead were three members of the minority Sikh community and two security officials.

The Orakzai region was for decades a refuge for Islamist militants fighting in Afghanistan, and more recently against the Pakistani state.

The Pakistani military stepped up operations along the border in 2009 and has managed to clear some areas of militants.