Chairman Eamonn McManus said Saints had "obtained an acceptable transfer fee" for Barba and would be announcing a new signing from the NRL in due course.

Barba, 29, joined in 2017 after a spell with French rugby union side Toulon.

The former NRL Grand Final winner has scored 26 Super League tries for League Leaders' Shield winners Saints in 2018.

He said playing for St Helens has been a "wonderful experience" and was "appreciative of the understanding and compassion" shown in allowing him to return to his native Australia.

• Ben Barba: The rugby league superstar you may never have heard of

Barba helped Cronulla Sharks to victory in the 2016 NRL showpiece, but was banned for 12 games soon after he tested positive for cocaine.

He went on to cross codes and join Toulon in February 2017 in a controversial move which saw him escape being sanctioned as the suspension only applied to rugby league.

The full-back eventually left Toulon and went on to sign for Saints in May 2017 but an independent panel upheld the decision to suspend Barba on his return to the sport.

Saints head coach Justin Holbrook said: "We would have loved to have kept Ben for next season but he wants to return home and to the NRL.

"It is hard to stop that from happening but it hasn't affected himself or the team with this decision."