Mozambican opposition leader Venancio Mondlane returned home on Thursday after fleeing days after a bitterly fought October election that sparked demonstrations in which scores of demonstrators were killed.
Mr Mondrain called on his supporters to take to the streets across South Africa, a country of 35 million people, claiming the October 9 poll was fraudulent.
“If you want to negotiate, I’m here to say it live…I’m here,” Mondrain told reporters in a message to authorities.
A heavy presence of riot police was felt around the capital Maputo’s international airport, where thousands of people gathered to welcome Mondlane.
A Reuters witness said tear gas was fired into crowds in the area and snipers were positioned in buildings around the airbase.
Protests have continued sporadically for more than two months, and Mondlane’s return could add fuel to the fire.
Civil society watchdog group Plataforma Decide said at least 278 people had been killed in protests since mid-October, when the electoral commission announced the ruling Frelimo party’s decision to extend its half-century in power.