Forty-six deaths were confirmed by dusk Tuesday and officials report another 14 bodies arriving in hospitals overnight. But Pakistani press reports put the number of deaths as high as 103.
More than 150 people are reported to have been wounded.
Traffic was thin on the city’s usually busy streets on Wednesday and most shops and fuel stations were closed, for fear of further violence.
The Pashtun-based Awami National Party (ANP) has angrily rebutted charges by the Muttahida Qaumi Movement (MQM) that its members were responsible for the killing of MQM Sindh provincial assembly member Raza Haider which sparked the violence.
The charges are “baseless”, Sindh ANP Secretary-General Amin Khattak told Dawn newspaper, adding that nine of his party’s members had been killed in the last month.
Although far from the centres of Taliban and Al-Qaeda activity in Pakistan, Karachi is plagued by crime and ethnic, sectarian and political violence.
Rights campaigners say that 260 targeted killings were reported in the first six months of this year, compared to 156 in all of 2009.