Dwain Chambers, the disgraced British sprinter, is to make a dramatic career switch to rugby league. Castleford Tigers, the bottom club in the engage Super League, are set to announce his signing on Monday.

Chambers, who this month finished second in the 60 metres at the World Indoor Championships in Valencia and served a two-year ban that ended in 2005 after testing positive for the designer steroid tetrahydrogestrinone (THG), had a brief dalliance with American football, but the move to rugby league has come as a bolt from the blue. It seems likely to mark the end of his athletics career and signal that he will not, after all, be contesting his life ban from the British Olympic Association in the courts.