IOC: The Winter Games in the Russian city of Sochi will see the "toughest ever" anti-doping tests, International Olympic Committee (IOC) president Thomas Bach says, despite scepticism over the host country's testing capability.

Bach, elected head of the IOC in September, said on Thursday the number of pre-competition tests at Sochi next year would increase 57 per cent compared with the previous Winter Olympics in Vancouver.

"We can clearly say that both as regards to quantity as well as quality, this will be the toughest anti-doping program we have ever had in the Olympic Games", Bach told journalists during a visit to South Korea.

"The tests will be even more target-oriented ... there will be more tests pre-competition ... where most of the anti-doping violations are happening," he said.

Bach arrived on Wednesday to inspect preparations for the 2018 Pyeongchang Winter Olympics.

He told the World Conference on Doping in Sport in Johannesburg last week that athletes would undergo 1269 pre-competition tests - over 400 more than at the Vancouver Games.

However, the global anti-doping agency this month provisionally suspended the accreditation of Moscow's sports drug-testing laboratory because of questions over the quality of its procedures.

Russia's sports minister has promised necessary measures would be taken at the lab, which has until December 1 to improve the reliability of its results.

Global leaders passed a new world anti-doping code at the conference in Johannesburg, under which offenders could face up to four-year bans from competitive sport.

The code has been backed by powerful sporting bodies such as the International Olympic Committee, world football's governing body FIFA and governments.

The revised world anti-doping code follows a two-year re-evaluation, during which the discovery of extensive doping by champion cyclist Lance Armstrong highlighted the challenges of ensuring clean competition.

Bach hailed South Korea's preparations for the 2018 Winter Olympics.

"We're satisfied with progress made by the organising committee. This progress makes us very, very confident about the success of the Winter Games in 2018," he said.

The eastern resort town of Pyeongchang will become the first Asian country to host the Winter Olympics after Japan.