England batsman Alex Hales has failed a drugs test. Hales, who was named in England's provisional 15-man World Cup squad last week, is understood by ESPNcricinfo to have tested positive for a recreational drug in recent weeks. The England selectors are not thought to have known about the test result at the time the squad was announced.

According to a report in the Guardian, he is currently serving a 21-day ban after returning a second positive test, having pulled out of Nottinghamshire's Royal London Cup campaign, shortly after the World Cup squad was announced, for undisclosed personal reasons.

An ECB spokesman said: "We have a duty of confidentiality, therefore we are unable to provide any further comment."

The drugs violation is understood to have been detected after Hales underwent a routine hair-follicle test, which all professional men's cricketers and centrally contracted women's players undergo at the start and finish of every season. The policy was introduced in 2013 in the wake of the death of Surrey's Tom Maynard, and can detect banned substances in the system for up to three months.

For a first offence, which is treated as a health and welfare issue, players are offered advice and support with few people being notified. They are the Professional Cricketers' Association (PCA) director of development and welfare, the ECB anti-doping and recreational drugs manager, the chief medical officers of the ECB and the county involved.

A second violation can invoke a three-week ban and a 5% fine of the player's annual salary, at which point the player's county is informed, as well as the ECB chief executive, Tom Harrison, and PCA chief executive, David Leatherdale.

A third offence, such as that committed by Durham's Jack Burnham in 2017, can lead to dismissal - although in Burnham's case, the club chose instead to ban him for 12 months and give him the chance to revive his career this year.

It is nevertheless another significant black mark for Hales, who was recently banned for six white-ball games (four of them suspended) and fined £17,500 by the ECB for his part in the Bristol brawl that led to Ben Stokes' arrest and subsequent acquittal. England are not obliged to name their final World Cup squad until May 23.

Although the loss of Hales at the World Cup would be significant, as things stand he would have served his suspension. He is still expected to join up with the squad for their training camp in Cardiff at the weekend and, according to reports, could be available for next week's ODI in Dublin and the subsequent five-match series against Pakistan.

While he is not currently seen as part of the first-choice side, he was set to be the reserve batsman in the squad. He has an outstanding ODI record: only nine men have scored more than his six ODI hundreds for England; only Jason Roy has a higher individual score in the format than the 171 Hales made against Pakistan. With Roy (back spasm) having recently experienced some fitness concerns, there was every chance he would win an opportunity at some stage during the tournament.

Ashley Giles, the England men's team director, and Mick Newell, Nottinghamshire's director of cricket, both declined to comment when contacted by ESPNcricinfo.