Benjamin was expected to stay with Jackson until at least 2008

The 25-year-old athlete teamed up with Welsh compatriot Jackson in September in a link-up that was expected to last until the 2008 Beijing Olympics.

But a statement on the UK Athletics website says Benjamin has opted to end the partnership with immediate effect.

"I believe this is the right decision for me with Beijing just around the corner," said Benjamin, who thanked Jackson for his efforts.

Interview: Colin Jackson

Tim Benjamin 400m Masterclass

Benjamin, who left coach Tony Lester to join Jackson's training group, was ranked fourth in the world in 2005 but saw his progress stall last season because of injury.

606: DEBATE Has Benjamin made the right choice?

The Cardiff star has made a gradual return to competitiveness this summer.

"It is important for our senior athletes to try new things as part of their training and long-term development," said UK Athletics performance director Dave Collins.

"We will now work with Tim to focus on getting him in the best possible shape for the rest of the season and to prepare him for the starting line in Beijing next year with the full and continuing support of UK Athletics."

I think my approach was all very new and very different for Tim Colin Jackson

Jackson, a double world 110m hurdle champion who took 400m hurdler Rhys Williams under his wing at the same time as Benjamin, says he has no problems with Benjamin's decision.

"I think my approach was all very new and very different for Tim," Jackson told BBC Five Live.

"I have a certain regime and he had not worked in that way before.

"Both Tim and Rhys have huge enthusiasm. But I don't think Tim felt 100% right so he made the right decision, for him, to move on.