Wigan are thought to have made a bid in the region of £4million for the striker, who enjoyed a superb debut season in the Premier League last term, scoring 15 goals to help the Baggies stay up.
Spurs are also keen on the Nigerian and he has admitted he would be open to a move away from the Premier League if one of the big boys came in for him.
Speaking on Twitter, the 30-year-old said: "To my dear WBA supporters. I love this club and will leave only to a TOP team which is understandable. Nothing abnormal is going on.
"Contract is not signed cos of the duration of it (sic). Figures agreed long time ago cos I know this is not Real Madrid. Please be patient."