Dwain Chambers is not expected to return to athletics until his prize-money dispute with the sport's governing body is resolved.
Chambers had planned to make his comeback in tomorrow's Norwich Union Indoor Grand Prix at the National Indoor Arena in Birmingham after completing a two-year drug ban imposed for failing a test for the anabolic steroid tetrahydrogestrinone (THG).
The European 100 metres champion has also successfully passed four mandatory International Association of Athletics Federations drug tests required before an athlete is eligible to compete again. However, Chambers said just before Christmas that he had been using THG since early 2002, prompting the IAAF to review his activities.
The IAAF then requested Chambers to further explain his comments via UK Athletics by February 21.
The 27-year-old was also asked to respond regarding how he might pay back some, or all, of the prize-money he accrued during this period - a substantial sum.
The ruling aimed at recovering cash from banned athletes was introduced by the IAAF in January 2004 following the furore caused by the THG scandal.
It is understood that, due to the timeframe, Chambers is the first athlete to be subject to the new regulation and he is not being deliberately targeted.
IAAF communications director Nick Davies said: "There is no question Dwain has complied with all of the re-eligibility procedures for the 2003 offence according to the rules of the IAAF relevant at that time.
"But what we now have is an interview with the BBC broadcast in December 2005, which is a new situation of a potential violation of current IAAF rules.
"We are continuing to investigate this in the case of Dwain Chambers but we understand he will not compete until the situation is resolved."
Davies said Chambers was not considered to have committed a second drugs offence and cannot again be suspended because the THG use occurred before the offence for which he served his punishment.
The Londoner was expected to make his comeback in Birmingham but has decided racing at world-class level might be counter-productive until everything is resolved with the IAAF.
"Dwain Chambers will not be running until the reinstatement procedures are fully completed," Richard Robson, his agent, said.
Chambers would first rather answer the IAAF queries - the main stumbling block likely to be the repayment of the money - starting afresh with a clean slate.