The incident occurred a few hours before Yousuf Raza Gilani, Pakistan's prime minister, was due to arrive in Karachi, Pakistan’s largest city.

However, there was no official indication that he was the target of the bombers.

Infomation from detainee

The raid on the bombers' hideout came after police gathered information from a member of Lashkar-e-Jhangvi, an outlawed Sunni Muslim group.

The informant had been detained in a raid carried out at dawn on Friday, Khattak said.

"We surrounded the area after the detainee told interrogators that his colleagues hiding there were heavily armed and also carried suicide jackets," Khattak said.

When police surrounded the property in Baldia, the fighters threw at least five grenades at them, although there were no casualties.

"The militants blew themselves up after their ammunition was exhausted," Khattak said.

Khattak said the individuals were sought in connection with a suicide bombing at a religious gathering in Karachi, in which 47 people died.

The raid in Karachi comes less than a week after at least 60 people were killed in a suicide truck bomb attack on the Marriott hotel in Islamabad, the Pakistani capital.

Fighters linked to al-Qaeda and the Taliban have claimed responsibility for several suicide attacks in recent weeks, but the Taliban denied involvement in the Marriott bombing.

They have said that the bombings were carried out in retaliation for Pakistani military offensives against opposition fighters in the northwest of the country.