Folan has already scored against Premiership teams this season

The 24-year-old has scored 12 goals for the League One club this season and caught the eye with a string of goals in their impressive Carling Cup run.

"I think the lad's got it, simple as that," said Latics boss Paul Jewell.

"He's strong, he's aggressive, he's got a finisher's instinct and he will add competition in an area where the squad needs bolstering."

Folan, who began his career as a trainee at Leeds, scored against Manchester City, West Ham and Charlton as the Spirerites reached the fourth round of the League Cup.

"I've watched the lad twice in person while the club has also scouted him on a number of other occasions, and I think he's got what it takes to play at the top level," Jewell added.

I just want to start training and start fighting for my place Caleb Folan

"I've always maintained I will never buy a player unless I think he can add something to my squad, and Caleb is no different."

Folan, who has also played for Rushden and Diamonds and Hull, said: "Every player dreams of being in the Premiership.

"Although it's difficult for me to leave Chesterfield because the club has been so good to me, this is an amazing opportunity and I want to repay the faith that Paul Jewell has shown by proving that I am good enough to play in the Premiership.

"There are some great players at this club and I cannot fail to improve by being here.

"Now, I just want to meet the lads, start training and start fighting for my place."