Cronulla backrower Reni Maitua's NRL career appears to be over with confirmation his B sample test for a banned substance has come back positive.

Maitua, 26, was told of the result by the Australian Sports Anti-Doping Authority (ASADA) on Friday, meaning he is facing a ban from the sport of up to two years.

The troubled former Test player last month returned a positive sample for the banned substance Clenbuterol, a stimulant used to boost muscle mass and strip body fat.

Maitua's agent Sam Ayoub told AAP on Friday his client had been told of the B sample's results and is now assessing his options.

"We need to work out our next step before we can make any comments," Ayoub said.

"The first thing we need to do is receive the official documentation on what our options are and then meet with our solicitors to work out our next step."

Maitua had only joined the Sharks in the off-season after he was dumped by the Bulldogs following several off-field indiscretions.

Ayoub said while the news Maitua's B sample had tested positive was bad news, it didn't confirm the end of his client's career.

"It depends on what action we can take from here," he said.

"Apparently, yes, we can take further action but I'm a bit naive on this, I haven't been through the process before."

Ayoub said he expects to receive the official documentation from ASADA on Tuesday or Wednesday next week.

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