Tests on the B samples of American athletes Kelli White and Chris Phillips, who tested positive for Modafinil at the Paris world championships in August, again revealed traces of the stimulant, French sports daily l'Equipe said on Thursday.

The newspaper, citing officials at the anti-doping laboratory which conducted the tests in Chatenay-Malabry, near Paris, said tests on the B samples took place earlier this week.

Double world sprint champion White now looks certain to lose both her 100 metres and 200 metres gold medals since the positive test was confirmed.

The International Association of Athletics Federation (IAAF) had referred the White case to the U.S. anti-doping agency (USADA) who are now expected to hand the case over to the World Anti-doping Agency (WADA).

White, who tested positive after winning the 100 metres on August 24, said she took the prescribed medication to combat narcolepsy.

Phillips finished sixth in the 110 metres hurdles final.

Modafinil is not yet on the IAAF banned list, but is closely related to other drugs which are.