World Anti-doping Agency (WADA) revelations about systematic doping by Russian athletes are "way worse than imagined", women's marathon world record-holder Paula Radcliffe said on Monday. (WADA report asks for banning Russian athletes for systematic doping)
"Suspected some of this for years but way worse than imagined," Radcliffe, 41, wrote on Twitter. "Athletics needs to take strong action and move quickly forward in right direction."
The three-time London and New York marathon-winner, an outspoken campaigner against dope cheats, added: "This is the time clean athletes need to stand up and fight for our sport and credibility."
Published on Monday, the report by WADA's independent commission outlined evidence of "state-sponsored" doping in Russia and called for the country to be banned from next year's Olympics in Rio de Janeiro.
Radcliffe, who retired from competitive running earlier this year, has previously called for harsher penalties against athletes found guilty of using performance-enhancing drugs.
In a statement sent to AFP, British Athletics said: "The findings of the WADA report published today in Geneva will be hugely significant and devastating for clean athletes not only in the UK but across the globe.
"We call upon the IAAF and all other relevant bodies to implement the recommendations in full to ensure clean athletes can compete in major championships against athletes and nations who embody the integrity of clean sport."
Britain won six medals in athletics at the London 2012 Olympics, including four golds, and seven medals at this year's World Championships in Beijing, again including four golds.