The bomber blew himself up at the residence of PML-N leader Rasheed Akbar Nawani, a prominent politician of Bhakkar district and a member of the National Assembly, almost destroying his home and shaking the entire area sending his panicked neighbours and shopkeepers scurrying for safety.

Nawani was injured in the attack and rushed to a hospital, where channels said his condition was serious.

Though TV channels reported that 25 people were killed, the interior ministry confirmed 20 deaths. The death toll could rise as many of the injured are in critical condition, witnesses said.

Punjab's Inspector General of Police Shaukat Javed said the head of the suicide bomber had been found.

Nawani's residence was sealed off by policemen and investigators scoured the site of the blast for clues. Police officials said the bomber's jacket, with an Afghan currency note inside it, had been recovered.

Over 200 people had gathered at Nawani's home to exchange Eid greetings at the time of the attack. Though special security arrangements were made at the lawmaker's residence, the bomber managed to sneak inside and detonate his explosives, police officials said.

Nawani is a Shia and reports suggested that the attack might have been carried out by rival sectarian groups.

No group has claimed responsibility for the attack, which was condemned by President Asif Ali Zardari, Prime Minister Yousuf Raza Gilani and PML-N chief Nawaz Sharif.