FIFA drug tested Russia's preliminary World Cup squad following the release of the McLaren reports and found "insufficient evidence" to assert an anti-doping rule violation.

The second part of professor Richard McLaren's report, published in December 2016, claimed over 1,000 Russian athletes across 30 sports, including football, had been involved in a doping conspiracy.

Ahead of this year's World Cup, FIFA took advice from McLaren and pre-emptively tested the country's initial 28-man squad for the tournament.

"FIFA can today confirm that the investigations concerning all Russian players named for the provisional squad of the World Cup in Russia have been completed, with the result that insufficient evidence was found to assert an anti-doping rule violation," FIFA said in a statement.

"FIFA has informed the World Anti-Doping Agency (WADA) of its conclusions, and WADA in turn has agreed with FIFA's decision to close the cases."

Football's governing body confirmed on Tuesday "high-level players against whom a suspicion had been raised" are being prioritised in their investigations.

The body added: "In accordance with the FIFA Anti-Doping Regulations and the World Anti-Doping Code, FIFA cannot provide any names of individuals involved in the investigations.

"Investigations of several players unrelated to the World Cup are still ongoing and FIFA will continue to work on these cases in cooperation with WADA. Further updates will be provided in due course."