Earl, 23, has been issued with an NRL infraction notice over an Australian Sports Anti-Doping Authority (ASADA) inquiry into banned substances in the sport.
The player has accepted the immediate provisional suspension and he will be given the opportunity to challenge the charges at a hearing. It is believed the charges relate to Earl's career before he joined the Raiders in 2012.
NRL chief executive Dave Smith said at a media conference that Earl had made admissions about the use and trafficking of the peptide CJC-1295 when interviewed by ASADA recently.
Smith said Earl, a former player with Sydney Roosters and Penrith who has signed a deal with French rugby union club Pau for next season, had volunteered to stand down while the charges against him were dealt with.
"Today's development reinforces the position we have taken from the outset and highlights our resolve in dealing with what are serious issues," Smith said.
"We continue to work with ASADA, the government authority in anti-doping, to get to the bottom of all allegations.
"We will act on evidence when it is fully available. Everyone should be in no doubt that ASADA is continuing its investigations and that we will continue to work closely with them.
"I stress that we do not have evidence at this stage that would warrant any further action against any individual or club. Our resolve on these issues remain clear.
"There is no place for drugs in our game and the sweeping actions we have taken in relation to new drug testing and the formation of the integrity unit this year underline our commitment in that area.
"The rights and welfare of the players also remains paramount and we continue to provide both welfare and legal support to them throughout this process.
"We want a safe environment for our players and that means a sport where there is no place for performance-enhancing drugs and no place for people who take risks with the well-being of athletes.
"We remain committed to a drug-free sport."