Portugal forward Luis Boa Morte has left Fulham to join struggling Premier League rivals West Ham United in their bid to avoid relegation.

The transfer fee was not disclosed by the two clubs on Friday, although media reports put it at 5.0 million pounds.

The 29-year-old winger, who joined Fulham initially on loan from Southampton in 2000, has signed a three and a half year contract and will go straight into the squad for Saturday's FA Cup third round tie with Brighton & Hove Albion.

Boa Morte becomes new manager Alan Curbishley's first signing as he tries to haul last season's FA Cup finalists out of the drop zone. They are currently 18th in the 20-team league, four points adrift of the next club, Wigan Athletic.

"West Ham is a massive club and I wouldn't have signed if I didn't think we could avoid relegation," he told West Ham's Web site (www.whufc.com). "I definitely believe we can improve, and I am excited about the challenge that is ahead."