It is the third bomb blast in Karachi in three days. Scores of peoples were injured in the two blasts on Saturday and Sunday, according to the police.

Karachi Mayor Mustafa Kamal asked the citizens to remain peaceful and do not show any reaction. He expressed shock over attacks on property and vehicles after the blast. He said that the blast was aimed at destroying peace of the city.

During the first Muslim month of Muharram, Shiites across the world mourn the death of the Prophet Mohammad's grandson Imam Hussain in the Iraqi city of Kerbala in the year 680.

Pakistan's security forces have been on high alert as Muslims are marking the holy day of Ashura, the Shia calendar's biggest event.

On Sunday evening at least 15 people, including mourners and policemen, were killed and over 100 injured when a suicide bomber ripped through a Muharram procession near a Shia mosque in the Pakistan-controlled Kashmir.

Pakistani President Asif Ali Zardari, Prime Minister Syed Yusuf Raza Gilani, political and religious leaders appealed all sections of society for calm and restraint and urged the people of Karachi not to be provoked by the "most reprehensible act of terror."

In a statement the president said that the fanatics wanted to provoke frenzy and riots to achieve their designs and called upon the people not to fall into their trap.