South Africa's embassy in Madagascar has granted refuge to two journalists and a technician of a closed-down opposition radio station following "prolonged harassment", it said on Friday.

"The South African embassy confirms that it has decided to give refuge to the journalists in question... because of prolonged and incessant harassment of these journalists and of others, as well as the closing of Radio Free FM," the mission said in a statement.

Free FM, whose director Lalatiana Rakotondrazafy is one of the journalists, was the main opposition radio station on the Indian Ocean island.

The station closed down voluntarily in July, citing intimidation by the army following a mutiny.

Rakotondrazafy and one of her journalists were detained in May for broadcasting criticism of strongman Andry Rajoelina's government.