The Cardiff-born 110 metres hurdles world record holder had promised to run at both the Welsh Championships and the Welsh Games.

But reports suggest Jackson will now compete in Prague on the same day as the Games in Cardiff.

Steve Brace, director of athletics at the Athletics Association of Wales revealed the growing concern that Jackson would not race on 8 July.

"I heard he is down to compete in an event in Prague on the same night as our Games," Brace told the Western Mail.

"I have left messages on his answerphone and with his agent, but I have had no feedback.

"He gave his promise back in February that he would be there, but it's still going to be a fantastic event with or without Colin."

The Welsh Games will be used as a warm-up for the up coming Commonwealth Games in Manchester, with teams from Australia, South Africa and the Caribbean descending on Cardiff's Leckwith Stadium.

Jackson has not commented on the issue, but this would not be the first time the Brecon AC hurdler has courted controversy.

On the eve of the 1998 Commonwealth Games Jackson pulled out of the squad claiming 'fatigue', only to race in a prize meeting in Tokyo on the day of the 110m hurdles final.

Last season Jackson rendered himself ineligible for this year's Commonwealth Games by refusing to compete at the Welsh Championships.

But AAW officials, desperate for Jackson to compete in Manchester, bent the rules for Wales' most successful hurdler, allowing him to join the squad.

The 35-year-old former world champion represents one of Wales' strongest medal hopes in Manchester.

Jackson's recent form has been impressive.

A time of 13.41 seconds secured victory in Dortmund on 8 June, and at the Welsh Championships in Newport the following day he brushed aside Welsh Commonwealth Games hopefuls with a winning time of 13.8sec.

On Sunday he set a two-year personal best with a time of 13.15sec to help Britain's men to victory at the European Cup in France.