Hart has made more than 100 league appearances for the Dons

Hart has signed a pre-contract agreement and is expected to move to Deepdale at the end of the season unless the clubs can agree a fee now.

Plymouth had already had a bid for the 27-year-old accepted by Aberdeen, but Hart, whose contract expires in the summer, has opted to join Preston.

Hart has made more than 100 league appearances for the Dons.

The Scottish Premier League club are unlikely to accept any less than the �200,000 offered by Plymouth to allow Hart to leave during January.

North End chairman Derek Shaw told his club website: "We made Aberdeen an offer earlier this month which was not accepted.

Ideally, we would like to agree compensation with Aberdeen in the January transfer window Preston chairman Derek Shaw

"I understand that Aberdeen have agreed a fee for two of their players with another Championship club.

"However, Michael has chosen to come to Preston and we are delighted with that.

"Ideally, we would like to agree compensation with Aberdeen in the January transfer window and Michael can start his Preston North End career sooner rather than later.

"However, if that doesn't happen then Michael will be our player in time for pre-season in the 2008-09 campaign."

MY SPORT: DEBATE He is a solid defender with a bit of pace on him to get up the line and stick in a decent cross. ScottDon

Aberdeen had last week announced that Hart, midfielder Barry Nicholson and forward Chris Clark had all rejected the offer of new contracts.

And director of football Willie Miller admitted at the time: "The fact is, if an English club comes in for a player, we can't compete.