Thompson has been a substitute on five occasions this season

Midfielder Thompson signed a short-term deal following his release by Rovers, while Mellor has joined on loan until the end of the season.

Mellor, 23, has not played under Rafael Benitez this season, while Thompson, 28, has made just eight appearances.

Wigan boss Paul Jewell has been looking to build on his side's start to the season which sees them lying sixth.

Thompson has suffered a host of injury problems over the last few years.

The difficulties started in 2003 when a knee ligament problem kept him out for nine months.

He broke two bones in his foot after just 17 minutes of his comeback game against Manchester United in August 2004 which forced him to spend three months on the sidelines.

Further surgery to finally correct the injury followed last summer.

Complications with his knee then arose on a pre-season tour of Germany and he has been restricted to just three starts this season.

"David has shown a real hunger to be involved with the Wigan project," said Jewell.

"He's a talented lad who can play in a number of positions and he also has an eye for goal.

"I only believe in bringing players in who add something new to our squad, and in signing David we have done that."

Blackburn boss Mark Hughes added that he felt the time was right to let the former Coventry player leave.

"It has been difficult for David. He has had a lot of injuries and he was coming to the end of his contract here," said Hughes.

"We have a lot of options in midfield, and it was a case of looking at the balance of the squad and seeing what we need for next year."