South African Gerco van Deventer, who had been held by militants in Mali for over six years, has been released, security and humanitarian sources told AFP on Sunday.

"We learned that the South African hostage was released the day before yesterday," a Malian security source told AFP.

A foreign humanitarian source confirmed the information, adding that Van Deventer was released on the border between Mali and Algeria.

The security source said that the freed hostage was currently under observation in a hospital in Algiers.

The two sources confirmed information given by South African NGO Gift of the Givers.

Van Deventer, 48, was kidnapped in Libya on November 3, 2017 on his way to a power plant construction site around 1,000 kilometres (600 miles) south of the capital Tripoli.

Three other Turkish engineers seized at the same time were freed seven months later, but Van Deventer remained in captivity and was moved to Mali.

In March his family launched a fresh appeal for his release. His wife said she and their three children "desperately need him home".

Van Deventer, an emergency paramedic, was working for a security company, his wife said at the time.