Pakistan's financial hub and largest city, Karachi, shut down Friday after the killing in London of a leading figure in a regional Pakistani political party, DPA reported.
Imran Farooq, a senior member of the Muttahida Quami Movement (MQM), died of stab wounds and head injuries after being attacked outside his north London home late Thursday, police sources were quoted as saying by the BBC.
Farooq had been living in London since 1999 after leaving Pakistan when he was charged with criminal offences in connection with the alleged strong-arm tactics of the party he co-founded in Karachi.
He claimed asylum in Britain, saying there was a bounty on his head from rivals in Pakistan, the MQM website said.
Demonstrations broke out in Karachi in response to the killing as the MQM declared 10 days of mourning Thursday, local media reported. Angry crowds set fire to several vehicles in the southern port city and held rallies in other cities in Sindh province.
On Friday, most businesses and educational institutions were closed. Public transport did not run, but no violence was reported, police said.
Karachi has a long history of violent protests and ethnic clashes. Around 100 people were killed last month after an MQM lawmaker was killed.
The MQM mainly represents the Urdu-speaking population, who migrated from India after the creation of Pakistan in 1947.
Its rival is the Awami National Party, which represents the Pashto-speaking population, who migrated from the north-western province of Khyber-Pakhtunkhwa over the decades to find work in Karachi.
Altaf Hussain, the MQM's chief, has led the party from exile in London since 1992. He condemned Farooq's murder.
Hundreds of protestors were gathering outside Farooq's family home in Karachi.
The London police told the BBC they had no suspects and no arrests had been made.