Martins has scored 11 goals this season so far for Newcastle

Nigeria threatened to report the club to Fifa for not letting Martins, 22, play in Tuesday's friendly with Ghana, but Newcastle say he is able to play.

A club statement said: "Newcastle wish to make it clear the club has not refused Martins permission to join up with the Nigerian squad.

"The club has written to the Nigerian FA to make that clear."

The Nigerian FA had threatened to involve Fifa if Martins, along with Chelsea midfielder Mikel Jon Obi, did not show up for training.

Nigeria take on Ghana on Tuesday at Brentford's Griffin Park ground.