The arrest in London of one of Karachi's most powerful politicians on suspicion of money-laundering has led to outbreaks of violent protest in Pakistan.
Altaf Hussain, leader of the The Muttahida Qaumi Movement (MQM), lives in Britain, but thousands of his supporters are protesting in Pakistan.
The (MQM) has its power base in Karachi, Pakistan's largest city, which it controls. The party urged supporters in Karachi to stay calm amid outbreaks of violence.
Vehicles were torched during the protests. Photo: AFP
Roads were jammed with traffic as people tried to get home, or rushed to stock up on food. Photo: AFP
Protesters torched at least a dozen vehicles, according to officials. Traffic jams were reported in Karachi and other cities in Sindh province as businesses closed and people headed home fearing violence.
British officials said they had temporarily closed their deputy high commission in the city, as Karachi police strengthened security in the city's diplomatic enclave, AFP reports.
Mr Hussain has lived in the UK since 1991, saying his life would be at risk if he returned to Pakistan, the BBC reports. He requested political asylum in UK in 1992, later gaining British citizenship, and continues to run MQM from north London.
Karachi is Pakistan's economic heart but is frequently rocked by ethnic, sectarian and militant violence and has one of the world's highest murder rates.
MQM supporters hold up photos of party leader Altaf Hussain at a rally in Karachi. Photo: AFP
Unlike Pakistan's other major political leaders who are largely drawn from the country's elite, Mr Hussain was born to a lower middle-class family that migrated from Agra in India during partition in 1947.
He founded the MQM party in 1984 to safeguard the rights of Mohajirs, the city's Urdu-speaking community which fled from India.
Many of them revere him for bringing them relative prosperity after the turbulent ethnic clashes of the 1980s. But critics accuse the party of resorting to extortion and violence to maintain its grip on power.