Griffin has signed a three-year deal

The 28-year-old has joined the Rams on a three-year contract which will keep him at Pride Park until 2010.

Griffin will have a swift reunion with his former team-mates as Derby entertain Pompey on the opening day of the Premier League season.

"Andy is an excellent player with a calm head and has a very good attitude," Derby manager Billy Davies told the club's website.

"Like Andy Todd he brings experience to the squad. I believe Andy Griffin has great years ahead of him. Every time I see him play he shows how consistent he is."

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The full-back started his career at Stoke before a �1.5m move to Newcastle in January 1998.

He made over 100 appearances for the Magpies before he exited on a free transfer to Pompey in the summer of 2004.

But in three years he has made just 38 league starts for the club and spent much of last season back at Stoke on loan.

He becomes the Rams' fourth summer signing, joining Todd, Robert Earnshaw and Tyrone Mears.