Khan took career-best figures of 9-138 against Essex in June

He has taken 69 first-class wickets this summer and the club accepts a new deal may prove impossible if he earns a recall to India's national team.

"I think he has enjoyed every minute but quite understandably he has international ambitions.

"He wouldn't want to commit at this stage so it is an ongoing thing," said chief executive Mark Newton.

"We will have to see if he gets picked for a one-day series in September with Australia and West Indies in Malaysia in terms of having a good idea of whether he is back in the fold or not.

"In the end we will have to wait for that and then have a conversation about next season."

Khan has played 42 Tests and 107 one-day matches for India, but has been out of favour since February after the selectors opted to try out younger seam bowlers.

At 27, however, he is still in his prime.

"He has produced the goods on the field and off the field he is a super bloke to deal with," Newton added.

"He is no hassle, he does the job and hasn't had any injury problems. What more do you want from an overseas player?"