An American Catholic nun, Suellen Tennyson, who was kidnapped by armed men in northern Burkina Faso in April has been freed, said Theophile Nare, the bishop of the local diocese of Kaya on Wednesday.

The 83-year-old nun, from the order of the Marianites of the Holy Cross, was taken hostage on April 5 in the parish of Yalgo where she had been serving since 2014.

"Sister Suellen is currently in a safe place and in good health," Nare said in a statement.

"At the moment we do not have information on the conditions of her release," he added.

The identity of the nun's kidnappers was not known when she was taken in the middle of the night.

Militant groups, some with links to al Qaeda and Islamic State, have taken over large swathes of territory in Burkina Faso and conduct frequent attacks on the army and civilians.

A Canadian was found dead after a kidnapping there in 2019.