The IAAF have provisionally suspended seven Russian athletes for doping offences.
Five of the seven - distance runners Yelena Soboleva, Tatyana Tomashova and Yulia Fomenko along with Darya Pishchalnikova (discus) and Gulfiya Khanafeyeva (hammer) - were due to compete at next month's Olympics in Beijing.
The other two athletes are Svetlana Cherkasova (800m) and Olga Yegorova (1500m/5000m).
The seven have been charged under IAAF rules 32.2 (b) and 32.2 (e) for a "fraudulent substitution of urine which is both a prohibited method and also a form of tampering with the doping control process", according to a statement from the world governing body.
The statement continued: "These rule violations were established following the deliberate storage of samples by the IAAF and re-analysis using comparative DNA techniques, and were the result of a specific investigation which was instigated and carried out by the IAAF for more than a year.
"The IAAF will make no further comment until a final decision has been taken by the ARAF (All Russia Athletics Federation), which now takes over the responsibility to adjudicate these cases."
The athletes have up to 14 days to request a hearing with the national member federation. If a hearing is requested, it must be held within a period of two months.
The absence of Soboleva, Tomashova and Fomenko would be a huge blow to the Russians' hopes of clinching a middle-distance medal in the Chinese capital.
Soboleva - the reigning 1500m world indoor champion - is the world leader over 800m and 1500m this year, while Tomashova was world champion in 2003 and 2005 and claimed silver at the Athens Olympics four years ago.
Fomenko finished second behind Soboleva over 1500m at the world indoor championships in Valencia earlier this year.
The two field-eventers are also of pedigree, with Pishchalnikova the reigning European discus champion and hammer thrower Khanafeyeva a former world record holder.
- More about:
- British Cycling Federation
- Performance-Enhancing Drugs
- Russian Politics
- Track & Field