Zak Hardaker, one of England's top rugby league players, was provisionally suspended after failing a doping test and missed out on selection for the World Cup on Monday.
The 25-year-old fullback, who plays for Castleford Tigers in the European Super League, tested positive for a banned substance following a game against Leeds on Sept. 8, England's Rugby Football League said.
Hardaker was suspended by Castleford on Thursday after the northern club was notified by UK Anti-Doping about the player's positive test. It meant Hardaker missed the Super League's Grand Final against Leeds on Saturday. Leeds, Hardaker's former club, won 24-6 as Castleford produced one of its worst performances of the season.
"I would like to apologize to my Castleford Tigers teammates, the staff and all fans for my enormous error of judgment," Hardaker said in a statement released by Castleford. "I was given an opportunity by this great club and in what has been one of the most important weeks in its history, I have let everyone at the club down. For that, I truly apologize."
Hardaker added that "in no way did I, nor would I, ever take a substance with the intention of enhancing my performance."
Hardaker, who is facing a suspension of up to two years if found guilty, was thrown out of England's squad during the last World Cup in 2013 for a breach of discipline.
Hardaker's unavailability left a cloud over England's squad announcement for the World Cup, which takes place in Australia and New Zealand from Oct. 27-Dec. 2.
There was no place in the 24-man group for South Sydney prop George Burgess but his brothers, Sam and Tom, were included along with five other players from the NRL.
Wayne Bennett, England's Australian-born coach, only included two specialist wingers in Ryan Hall and Jermaine McGillvary and two specialist centers in Kallum Watkins and Mark Percival. Fullback Sam Tomkins missed out after an injury-hit season in the Super League with Wigan.
Second-rower Ben Currie is a newcomer in the squad. He played for Ireland in the last World Cup in 2013.
England will fly out on Thursday for a 10-day camp in Perth, Australia, and will play a warm-up match against an Affiliated States team on Oct. 20. The opening game of the World Cup is between Australia and England in Melbourne.
Squad: John Bateman, Kevin Brown, Sam Burgess, Tom Burgess, Ben Currie, Luke Gale, James Graham, Ryan Hall, Chris Heighington, Chris Hill, Josh Hodgson, Jonny Lomax, Jermaine McGillvary, Mike McMeeken, Sean O'Loughlin (captain), Mark Percival, Stefan Ratchford, James Roby, Scott Taylor, Alex Walmsley, Kallum Watkins, Elliott Whitehead, Gareth Widdop, George Williams.