The government in the Pakistani province of Sindh has declared a day of mourning after a suicide attack in its capital, Karachi, killed 40 people on Monday. Government offices are closed and security is tight ahead of the funerals of the victims. Security forces have been on high alert as Shia Muslims marked the holy month of Muharram. The main political parties in Sindh have called for a business and transport strike in protest against the violence.<br/>