Businesses and shops closed in the Ethiopian capital, Addis Ababa, as confrontation escalated between Ethiopian security forces and groups of students and demonstrators.

Clashes followed an order by Minister of Education Genet Zewde on Wednesday for police to enter the Addis Ababa university campus to "safeguard the welfare of students who want to continue with their studies", government-run Radio Ethiopia said.

Bystanders deserted the city streets as the government ultimatum for striking students expired at noon on Wednesday. Local sources said from the outskirts of the city that there had been "the sound of shooting in parts of the city" and "a lot of activity between police and groups of students".

Groups of students had "expanded" to include other demonstrators, the sources said. Business and shops had been forced to close after rioters threw stones through windows and doors, as large groups gathered in the town centre, the local sources said. Diplomatic sources in Addis Ababa confirmed reports of shooting and injuries.

The Ministry of Education told striking students to return to classes by noon on Wednesday on pain of expulsion.