KARACHI -- A senior government official was shot dead in central Karachi on Monday - the second such attack targeting high-profile minority Shiite sect members in the violence-prone port city, in less than a week.

Two motorcyclists opened fire at Syed Zafar Hussain only yards from his home in Nazimabad, a middle-class residential district in central Karachi, DPA quoted police as saying.

According to witnesses, Hussain, 50, was just stepping into his car to leave for his office when he was hit, receiving several bullets.

He was research director at the Ministry of Defense, based in the port city.

The two unknown motorcyclists fled. Police have made no arrests so far.

On Thursday, Shaukat Raza Mirza, managing director of the state-run Pakistan State Oil (PSO) was shot dead by unknown motor cycle riders in Karachi, Pakistan's commercial center.

Mirza was being driven to his office in the city center when his car was sprayed with bullets. He and his driver were killed on the spot.

A senior police officer had linked his death with sectarian violence involving the majority Sunni and minority Shiite Muslim communities in Pakistan.

At least 50 people have been killed in Karachi this year, most of them Shiites, in revenge attacks by rival sectarian organizations.