Abidjan - Ivory Coast's main port of Abidjan, one of Africa's biggest, was shut down on Wednesday when angry security forces began firing into the air during protests by mutinous troops, port staff said.Port management later issued a statement saying it was working to ensure that operations could resume."Port authorities and the state's services have implemented security measures leading to a return to calm at 11:30 ," management said in a statement."These measures are still in place now, permitting port operations to resume as normal."It was not immediately clear whether the port had reopened.Earlier, port staff in the world's top cocoa producer said paramilitary police involved in a mutiny over pay had fired into the air at the port at around 10:00."Then they chased us away. Everyone left," a port employee told AFP, asking not to be identified.