Police say 14 locations across six countries have been searched as they investigate possible doping offences in cycling.
Officers from France, Belgium, Spain, Croatia, Italy, Poland and Slovenia were involved in the raids which took place between 27-30 June.
They were co-ordinated by European crime agencies Europol and Eurojust.
The searches came just days before Friday’s start of the Tour de France, which begins in Copenhagen, Denmark.
Europol said that that following the raids on the properties of several riders and their staff, three people were questioned and that evidence seized was being forensically examined.
They added the “co-ordinated action against the use of prohibited substances in cycling races” also saw Danish Police search “one of the Tour de France hotels in Copenhagen”.
They did not name any individuals or riders involved.
However, on Thursday, Copenhagen police confirmed they searched hotel rooms and cars of Bahrain Victorious riders and staff.
It was the second time in a week that the team had been searched and comes after French prosecutors opened a preliminary investigation into doping allegations against them after police searched the team’s hotel late in last year’s race.
The team has denied those allegations.
Questions about Thursday’s raids were asked at Bahrain’s pre-Tour press conference on Thursday afternoon, but riders Matej Mohoric of Slovenia and the Australian Jack Haig refused to answer.
Europol added that a dozen officers had been deployed across the countries “to facilitate the extensive exchange of information and provide forensic support for the seized electronic devices.”