An 88-year-old Australian doctor held hostage in Africa for more than seven years by al Qaeda-linked militants has been reunited with his family after being released.

Dr Ken Elliott and his wife Jocelyn, who together ran a medical clinic in Burkina Faso, were kidnapped in 2016 by al Qaeda in the Islamic Maghreb (AQIM) - an African affiliate of the jihadist group.

Mrs Elliott was released three weeks later following a joint effort by Burkina Faso's intelligence service and the then president of neighbouring Niger, Mahamadou Issoufou.

On Thursday, Australian foreign minister Penny Wong said Dr Elliott had now been released and had since been reunited with his wife and children.

"I'm very pleased to advise that Dr Ken Elliott, who's been held hostage in Western Africa for some seven years, has been reunited in Australia with his family," she said in a statement.

No further details were disclosed about Dr Elliott's release, but Ms Wong said no ransom had been paid.

"The Australian government has a clear policy that we do not pay ransoms," she added.

"What we have done over the last seven years is ensure that we worked with other governments and local authorities in relation to Dr Elliott."

A family statement said: "We wish to express our thanks to God and all who have continued to pray for us.

"We express our relief that Dr Elliott is free and thank the Australian government and all who have been involved over time to secure his release.

"At 88 years of age, and after many years away from home, Dr Elliott now needs time and privacy to rest and rebuild strength."

Dr Elliott and his wife were kidnapped by AQIM near the northern Burkina Faso town of Djibo in January 2016.

The militant group, deemed a terrorist organisation by the UN and countries such as the US and UK, operates from Algeria's Kabylia mountains and in areas of Mali, Libya, Niger and Mauritania.

It rose to prominence in large part through kidnap-for-ransom operations targeting foreign aid workers and tourists.