Ellington has just 12 months left on his current deal and has yet to come close to agreeing a new deal.
Ellington's agent confirmed: "I can't deny Albion are interested in him.
"Their chief scout Bobby Hope has liked him ever since he was at Bristol Rovers four years ago, but at the time there was different management at the club."
Meanwhile Baggies' boss Bryan Robson has reiterated there was no chance of Wales striker Earnshaw moving in the opposite direction as part of the deal.
He said: "Earnie scored 11 goals for us last season - if you go out and try to buy somebody who can score 11 in the Premiership it is really difficult.
"He is an important part of the squad and he knows that."
Ellington joined Wigan in 2002 for a club record £1.2m from Bristol Rovers and has been impressive in the club's rise from the Championship.