The 31-year-old Londoner, who in 2006 completed a two-year ban for using the steroid Tetrahydrogestrinone (THG), was barred from the Olympics last year because of British Olympic Association (BOA) rules, but is part of the 60-strong team named by UK Athletics.

 

 

He will compete in the 100 and 200 metres but is not expected to be selected for the 4x100m relay because he is ineligible to compete in London 2012.

 

Defending 400m champion Christine Ohuruogu is also included despite concerns over a hamstring injury that caused the Olympic gold-medal winner to miss last week's Aviva London Grand Prix.

 

Chambers was beaten by Simeon Williamson at the British trials in Birmingham this month but UK Athletics have given him one of the two other 100m spots along with Tyrone Edgar.

 

It will be his first appearance at an outdoor World Championships since Paris in 2003 shortly before the sport and Chambers was enveloped in the doping scandal triggered by an investigation into the Bay Area Laboratory Co-Operative (Balco) in San Francisco which rocked the sport and continues to overshadow it today.

 

Chambers took a week's rest after his disappointing display in Birmingham, which he blamed on tiredness.

 

He said: "I'm not making any excuses but I was suffering from a lack of energy."

 

During May and June Chambers clocked up around a dozen races, including 100m and 200m victories for his country at the European Team Championships.

 

Chambers said: "I was just exhausted, I had too many races.

 

"In Birmingham I just wasn't there.

 

"I'm okay now, I've had 10 days of hard training and I am preparing for Berlin."

 

Chambers has struggled to repair his tarnished reputation since returning to competition, briefly flirting with careers in American football and rugby league, although he is the current European and world indoor champion.

 

He is banned by Europe's leading meeting after describing in his autobiography published earlier this year how he had taken 300 different concoctions of drugs before eventually testing positive for THG in 2003.

 

Charles van Commenee, Britain's head coach, said: "This team has been selected to give us the best possible results at the 2009 IAAF World Championships in Berlin.

 

"I expect to see athletes demonstrating their ability to perform at the highest level under pressure."

 

Marathon world record holder Paul Radcliffe, the 2005 world champion, and European Indoor 3,000m champion Mo Farah will also be in the team that will prepare in Portugal next week for the Championships, which open on August 15 and run until August 23.