Around 4,000 people blocked the main thoroughfare of Pakistan's port city of Karachi late Tuesday to protest the arrest of Altaf Hussain, the powerful exiled leader of the MQM party.
They were responding to a call by a senior party figure, Haider Abbas Rizvi, who said "Everyone should come to endorse his or her love and solidarity to Altaf Hussain."
He called for the sit-in on the city's MA Jinnah road to continue until Hussain, who was arrested in London on suspicion of money-laundering, was released.