Doctor Suraiya Nisar was shot dead as she came out of an operating theatre in the Al-Zohra Hospital, local police chief Muhammad Usman said, adding the attackers arrived at the hospital on a motorbike. One stayed at the main gate of the hospital while the other entered the premises and sprayed the doctor with bullets as she emerged from surgery, Usman said.

The assailants fled on the motorbike, witnesses said. They also shot at Nisar�s driver as he tried to chase them, wounding the man, the witnesses said.

The "possibility of terrorist activity cannot be ruled out," Usman said, adding "Police are investigating this case from all aspects, whether it is sectarian killing, or the motive was personal rivalry."

"We have no enmity, we have friendly relations with people of all sects. I am confident that it was a sectarian killing," said her brother, Iftikhar Hussain, himself a doctor.

Local Shia leader Syed Nadeem Haider told reporters: "We believe it is a sectarian killing because doctor Suraiya Nisar�s family was on the hit list of terrorists since long and they received threats in the past."

After the attack tension gripped the city, as hundreds of people gathered outside the hospital, chanting slogans against the government.