A US aid worker and French journalist who had been kidnapped by militants in West Africa have been released. 

Jeffery Woodke and Olivier Dubois were seen leaving a plane that landed at an airport in Niger's capital, Niamey, on Monday.

Mr Woodke went missing in Niger in 2016, while Mr Dubois was held hostage in neighbouring Mali for nearly two years.

Their release was secured following efforts by authorities in Niger.

Speaking in Niamey, Mr Dubois, 48, said it was "amazing for me to be here, to be free".

"I want to pay tribute to Niger for its skills in this delicate mission and pay tribute to France, to all those who have helped me to be here today," he told journalists.

Mr Woodke's release was announced days after US Secretary of State Antony Blinken travelled to Niger for an official visit, becoming the first top US diplomat to do so.

White House National Security Adviser Jake Sullivan said he was "relieved" and thanked the authorities in Niger for "bringing [Mr Woodke] home to all who miss and love him". 

"I thank so many across government who've worked tirelessly toward securing his freedom," he added in a tweet.