About 16,000 doping tests on 6,000 potential Winter Olympic athletes have been carried out ahead of the PyeongChang Games, the International Olympic Committee says.
It says the tests were carried out between April last year and January on athletes from more than 60 countries who are possible competitors in South Korea.
This is a two-thirds increase on pre-competition tests from ahead of the previous 2014 Games in Sochi.
Russia are banned from Pyeongchang over a state-sponsored doping program in the country and at the Games they hosted four years ago, though individual Russian athletes can compete as neutrals.
"It's not about more and more and more, rather than having as high a quality of control as possible," Richard Budgett, IOC medical director, said.
The focus of the tests was on the top 20 athletes in every sport and all Russians attending have also been tested.
Around 2,500 doping checks are expected to be made in PyeongChang, including 1,400 tests in training.
As a result of the Russian manipulations of samples in Sochi, security measures have been increased in the Seoul Analytical Laboratory, where video surveillance is monitored round the clock. The laboratory team also includes the heads of four other World Anti-Doping Agency laboratories.
