The NRL's Integrity Unit is investigating "very serious" allegations made against former South Sydney Rabbitohs player Sam Burgess.
A report in The Australian published on Friday accused Burgess of domestic violence and drug use, while claiming the Rabbitohs tried to cover up his actions.
Mark O'Brien, the lawyer acting for Burgess, refuted the claims with a widely released statement reading: "The allegations are false and constitute an indefensible defamation against my client.
"It is apparent sources of the false allegations are those currently in dispute with my client over various issues."
The NRL said its Integrity Unit has been instructed to launch a "comprehensive investigation" into the allegations made against the Rabbitohs and Burgess, who has stood down from his role as a coach at the team.
NRL Chief Executive Andrew Abdo said: "These allegations are very serious and I've instructed the Integrity Unit to investigate the claims as a priority. We will also seek the advice of police and other relevant authorities throughout this process.
"This is new information for the NRL and it is important we now gather the facts. The allegations have not yet been tested and due process will be followed as we undertake a thorough investigation.
"There is no place in our game for violence, harassment or abuse against women. If anyone is found guilty of these allegations we will take the strongest possible action."
The Rabbitohs said they welcomed the investigation and will cooperate fully.
"The allegations in today's The Australian newspaper are very concerning and the club is treating them with the utmost seriousness," a club statement read.
"There is no place in our society for violence, harassment or abuse against women. If anyone is found guilty of allegations of this nature, the club will take the strongest possible action.
"The club takes issues of drug use very seriously and has well-established policies and procedures in place around the use of performance enhancing or illicit/recreational/prescription drugs.
"The club will continue to work closely with ASADA and the NRL which administer testing of the players. The club will also continue to work with the playing group to support their wellbeing and educate them about drug use.
"The Rabbitohs welcome the NRL Integrity Unit's investigation in relation to these allegations and will fully cooperate with the investigation. The club is supportive of Sam Burgess's decision to step down from his role at the club while the NRL Integrity Unit investigation is underway."
Burgess won an NRL Grand Final with the Rabbitohs in 2014 and returned to the Sydney club in November 2015 following a short and unsuccessful stint in rugby union with Bath.
He represented England in the 15-man game at their home Rugby World Cup in which they were eliminated in the group stages.
