The latest figures show that 24,430 samples - urine, blood and Athlete Biological Passport - were collected in May 2021 by 152 ADOs, which is the highest number of samples collected since the pandemic started in March 2020.

The figures also show how testing dropped away dramatically during April and May last year, when the corresponding figures were 578 and 2,675.

That figure rose steadily, with 7,706 tests in June, 11,081 in July, 14,619 in August and 18,699 in September.

Despite continuing restrictions throughout many parts of the world, out-of-competition testing is now at a level greater than for the same period in 2019.

Specifically, in April 2021, 14,560 out-of-competition tests were carried out compared to 12,713 in April 2019.

In May, the number went up to 16,149, compared to 13,691 for the same month in 2019.

This was the highest number of out-of-competition samples collected over the past 29 months.

In-competition testing figures for May 2021 were also the highest in the past 15 months, with 8,281 samples collected from events and competitions.

WADA's director general Olivier Niggli said: "The rise of testing numbers around the world represents a significant effort on the part of Anti-Doping Organisations in light of the ongoing pandemic.

"WADA thanks them for their commitment, flexibility and determination to deliver a quality testing programme in challenging circumstances.

"With just over a month to go before the start of the Olympic Games, Anti-Doping Organisations are in the final phase of delivering on their strategic testing plans.

"WADA urges them all to continue to make the most of this time to ensure that all athletes bound for Tokyo have been properly tested and to implement the testing recommendations they have received from the Pre-Games Expert Group led by the International Testing Agency (ITA)."

The Pre-Games Expert Group has issued test recommendations to all the Summer Olympic International Federations and National and Regional Anti-Doping Organisations for athletes likely to participate at Tokyo 2020.

"I would also like to remind all Anti-Doping Organisations that the International Olympic Committee (IOC)-funded pre-Olympic long-term storage programme delivered by the ITA is available to them, at no cost, so they can securely put samples away in a long-term storage facility for possible further analysis in the months and years to come," Niggli added.

“As detection methods are constantly being improved and updated, retaining samples for up to 10 years means that those who have taken a prohibited substances cannot rest easy for a full decade after they have been tested.

"The storage and further analysis of samples has yielded considerable success in previous years and it is a requirement under the 2021 International Standard for Testing and Investigations that Anti-Doping Organisations must have a written strategy for storage and further analysis as part of their testing programmes.

"The further analysis of samples collected during the Beijing 2008 and London 2012 Olympic Games by the IOC has so far produced more than 130 anti-doping rule violations, which clearly highlights the effectiveness of such a programme to provide more effective detection.

"I am confident that this programme will continue to have further impact in the years to come."

WADA said it is working to ensure that it accredited laboratory in Tokyo will be ready for the challenge of the Olympics and Paralympics.