A suicide bomber blew himself up in northwest Pakistan Monday, killing at least eight people and injuring 21 in an attack the Taliban said was revenge for the hanging of one of its members last week.

A suicide bomber blew himself up in northwest Pakistan Monday, killing at least eight people and injuring 21 in an attack the Taliban said was revenge for the hanging of one of its members last week.

The bomber attacked as lawyers and litigants were arriving at a court complex during the morning rush hour in the town of Shabqadar.

"A suicide bomber blew up himself inside the court complex. So far eight people have been killed and 21 others are injured," Fayaz Khan, a senior police official in the area, told AFP.

Sohail Khalid, district police chief in Charsadda district where Shabqadar is located, confirmed the suicide attack and said two of the dead were policemen.

"We are investigating the nature of the blast. According to initial reports, a suicide bomber entered the complex and a policeman on duty tried to stop him but he blew himself up," Khalid said.

The Pakistani Taliban's Jamat-ul-Ahrar faction claimed responsibility for the attack, saying it avenged the hanging of Mumtaz Qadri, feted as a hero by the extremists after he gunned down the liberal governor of Punjab in 2011 over a call to reform the country's blasphemy law.

Qadri was hanged last Monday, with his funeral bringing up to 100,000 people on to the streets.

The Taliban also said Monday's blast targeted the court complex as Pakistan's judiciary are strengthening "un-Islamic laws", Ehsanullah Ehsan, a spokesman for the group told AFP.

Police official Khan said a woman was among the dead, and two children were among the injured.

Local TV channels showed footage of victims being rushed to hospitals soon after the blast.

Shabqadar is near the Mohmand tribal district, one of seven semi-autonomous regions bordering Afghanistan where militants from Al-Qaeda and the Taliban had established bases in the past.