Altaf Hussain, the leader of Pakistan’s powerful MQM party, has been arrested by British police, reportedly on suspicion of money laundering.
Hussein was detained at his home in London. He has lived in self-imposed exile in the UK since the early 1990s.
The MQM party has called for calm from its supporters. But protests have erupted in Pakistan’s largest city Karachi, where the party has a huge support base.
The MQM represents the interests of millions of Urdu-speaking descendants of Muslims who moved to Karachi and the surrounding areas at the time of the 1947 partition of India.
Parts of Karachi have been locked down due to concerns that the protests could escalate into violence.