Chambers was banned for two years in 2003 after testing positive for the designer drug THG and has not undergone an out-of-competition test since 2006.

UKA insist he must be regularly drug-tested over the next 12 months before they will consider him again for GB selection.

However, his lawyers, Ford and Warren, have made it clear if he is excluded from the trials they will take immediate legal action.

Chambers claimed it was UKA's decision to take him off its drug-testing register.

"I am trying to be diplomatic because I do not want to hinder my chances of getting to the trials," he said.

"But I never took myself off the drugs register. It was their decision and, unfortunately because of that, it has left both of us in a sticky situation.

"I never said I am retiring. I am back on the register and about three weeks ago I was tested. I always kept the IAAF informed about where I was."

Chambers announced he was returning to athletics a month ago after trying unsuccessfully to carve out a career in American football.

The IAAF, athletics' world governing body, has said he is free to continue his stop-start career "from an anti-doping rules perspective".

Entries for the meeting close at midnight on Sunday and a legal battle is certain to ensue if he is prevented from competing in Sheffield.

The Championships take place in Valencia from 7-9 March.