The Muttahida Qaumi Movement, the single largest party in Pakistan's biggest city, held an "emergency" news conference after midnight yesterday at Karachi Press Club to protest the arrest of its leader Fahad Aziz.
Aziz was detained while travelling from his home to the venue of his wedding.
The MQM central committee gave the Sindh government 24 hours to confirm the whereabouts of Aziz and to take action against the policemen who arrested him. It indicated it could launch a protest if no action was taken.
Provincial Information Minister Sharjeel Memon announced that four policemen, including the investigating officer, had been suspended. He said departmental action will be taken against the suspended personnel after a probe.
The incident came a day after the MQM enforced a strike in the city to protest alleged extra-judicial killings and enforced disappearances of its workers.