Fulop is Hungary's first-choice goalkeeper (Getty)

With Darren Ward back from injury Keane feels it would benefit both parties for Fulop to be playing regular football.

"I have a gentleman's agreement with Marton that if a club comes in that suited everybody we'd let him go," he told BBC Radio Newcastle.

"I think it's a good move for him in terms of getting games under his belt."

Interview: Sunderland boss Roy Keane

Fulop, 24, has already enjoyed a loan spell at Leicester this season but has struggled to break into the first-team at the Stadium of Light.

Keane is sympathetic to the pressure this has placed on his international prospects.

"Marton played an international match two weeks ago and has been told by his manager in no uncertain terms that he needs to be playing games," he said.