The 32-year-old midfielder has found first-team opportunities limited at Upton Park this season and Blues manager Alex McLeish is delighted with the capture.

McLeish said: "Lee's a dynamic player and I want to bring a dynamic look back to the team.

one goal

"Roy Aitken, one of my assistants, has worked with him at Leeds and knows him as an attacking midfielder but he also knows that Lee can give a lot to the team as well."

Bowyer rejoined West Ham when he returned to the Boleyn Ground from Newcastle United in June 2006 but so far this campaign has featured in only seven matches for the Hammers, scoring one goal - in the club's 4-1 Carling Cup win over Macclesfield Town.