The Bulls announced Platt's arrival at the club in October, in the belief that he had become a free agent after the Tigers' relegation from Super League.

Castleford denied the 22-year-old had a release clause, and after a Rugby Football League tribunal ruled in their favour, the Bulls had to pay a fee.

"We wish Michael well," said Tigers chief executive Richard Wright.

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"He has done a good job for us in his two years here and was a stand-out player in 2005 helping us to promotion for which we thank him.

"We paid a small fee for him when he came from Rochdale which we have recovered and also received some compensation for his development."

Bradford have signed Platt as a replacement for Michael Withers, who has moved to Wigan.

Platt has agreed terms on a two-year-deal.