Green has two years left on his current contract and it has been rumoured that the Hammers were prepared to cash in on one of their assets if a suitable bid were forthcoming.
Speaking to the Guardian Sullivan said, “I hope Robert does have a long-term future at West Ham,”
"We've got a fantastic new goalkeeping coach who I think will improve him dramatically.
"You're never too old to learn and I think he'll learn a lot."