Parramatta Eels star Michael Jennings has been provisionally suspended under the NRL's anti-doping policy following a positive drugs test.

The NRL on Saturday announced Jennings returned a positive A-sample for banned substances Ligandrol and Ibutamoren, and three of their metabolites – the day Parramatta are scheduled to meet South Sydney Rabbitohs in the semi-final.

Jennings – a former New South Wales centre and Tonga international who won the NRL premiership with Sydney Roosters in 2013 – now has the opportunity to have his B-sample analysed.

The 32-year-old was tested on September 21 with the result received by Sport Integrity Australia on October 9.

It is a huge blow for the Eels, who are looking to reach their first NRL Grand Final since finishing runners-up in 2009.

"The Parramatta Eels have today been made aware of the provisional suspension handed down to Michael Jennings under the NRL's Anti-Doping Policy," the club's statement read.

"Details of that provisional suspension and alleged breach of the anti-doping policy will be outlined in an NRL Media statement to be distributed today.

"Michael Jennings has been stood down from today's game and ongoing training/playing responsibilities while the process runs its course, which under the policy includes the opportunity to have his B-sample analysed.

"The club has been in contact with Michael and will continue to offer him and his family our full wellbeing support."

Jennings joined the Eels from the Roosters at the end of the 2015 campaign, having previously played for Penrith Panthers.

He signed a new deal with the Eels in July, keeping him at the club through the 2021 season, with an option for 2022.

This season, Jennings has made 20 appearances, scored seven tries and supplied four assists.