Twin blasts targeting Shiite Muslims killed up to 22 people in the Pakistani port city of Karachi on Friday, police and health officials said.

The attacks in two hours time also injured over 50 people, they said.

People around the scene of a blast in the Pakistani port city of Karachi on Februray 5, 2010.

Karachi Police Chief Wasim Ahmed said that a bomber rammed his explosive-packed motorcycle into a bus carrying Shiite Muslims at M.A. Jinnah road locality.

Health Minister Dr Sagheer confirmed that 12 people were killed and 50 others were injured in the first blast.

At least 10 people were killed and more than 20 others injured as the second blast hit the city outside Jinnah hospital, police said.

The blast occurred at the gate of emergency ward of Jinnah hospital where the wounded of an earlier deadly suicide attack on mourners were being treated.

The bomb was planted in a motorcycle parked at the hospital. Some ambulances were damaged and some rescue workers were injured, sources said.

The injured are now being rushed to other hospitals after the blast.

Witnesses said over 100 people, including relatives of the victims of the first blast and those who wanted to donate blood, were present near the emergency ward when the second blast happened.

Police and bomb disposal squad launched search operation in the area.

No group claimed responsibility for the attacks.

Pakistani Prime Minister Syed Yusuf Raza Gilani strongly condemned the attacks in Karachi and ordered immediate inquiry into the incident.

He also ordered the authorities to provide best medical facilities to the injured.

It is the second time that Shiite Muslims have been targeted in Karachi in less than two months. On December 28, 2009, a bomb blast killed 47 Shiite Muslims in the country's biggest city.