Sebastian Coe has branded the latest corruption claims to engulf athletics as "abhorrent".
The president of the sport's world governing body also again rejected accusations the organisation he now heads had been complacent in its handling of doping allegations.
The former Olympic champion was speaking after claims his predecessor Lamine Diack had received more than €1m to cover up cheating.
In his first response to the fresh crisis to hit the sport, Mr Coe said: "That people in our sport have allegedly extorted money from athletes guilty of doping violations is abhorrent."
The French authorities have placed Diack, the former president of the International Association of Athletics Federations (IAAF), under formal investigation on suspicion of corruption and money laundering.
The 82-year-old is alleged to have been paid bribes in 2011 to cover up positive doping tests of Russian athletes, the office of France's financial prosecutor said.
One of Diack's sons and three other sports officials, two who held IAAF positions, have also been charged with ethical violations by the governing body.
Coe said: "That they were not able to cover up the doping results is testament to the system that the IAAF and WADA (World Anti-Doping Agency) have jointly put in place."
Pledging tougher action by the IAAF under his leadership, Coe said: "Where there are fragilities in the system that may have allowed extortion, no matter how unsuccessful, we will strengthen them."
The former track and field athlete also dismissed criticism that the IAAF had not done enough to control doping.
He said: "Every doping case currently being investigated by WADA was first identified by the IAAF through its athlete biological passport (ABP) programme.
"We are not complacent. Every athlete found in violation has been charged and sanctioned."
Coe pointed out the IAAF had tested more than 5,000 athletes since 2009, as evidence the organisation was serious about cleaning up the sport.
He said: "The best way to cover up an anti-doping case is not to test athletes at all.
"We will continue to lead the fight against drugs in sport on behalf of all clean athletes.
"Those that cheat will be caught. Those that are caught will be thoroughly investigated and the guilty will face the fullest sanctions available."
The architect of the London 2012 Olympics was only elected to the top job in world athletics in August.
He took over at a difficult time for the sport, with serious doping allegations levelled against athletes and the governing body, and with public confidence eroded by decades of proven cheating.
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