Widnes have released half-back Anthony Watts with immediate effect, less than a week after he signed a new deal.
The 25-year-old half-back, who can also play at hooker, arrived at Vikings from Sydney Roosters in 2011 and had committed his future until 2013.
Meanwhile, Simon Finnigan is likely to miss the rest of the season.
The back-row forward suffered a fractured fibula and ruptured medial ankle ligaments in the
"I realised at the time that it was a bad injury but there's always that feint chance that things may not be as bad as first feared," said Finnigan.
"Unfortunately, it's turned out to be the worst case scenario and I'm absolutely gutted."
Watts suffered a season-ending injury 10 minutes into his Super League debut against Salford in February.
The Australian said: "I'd like to thank Widnes Vikings for the opportunity, but I need to return home for personal reasons."
The former Cronulla Sharks and North Queensland Cowboys player continued: "As I suggested recently, I genuinely believe the club will be a huge force within the next few years and go on to achieve great things in the game.
"Unfortunately, I won't be a part of that but I hope the fans continue to show the passion and commitment that I have witnessed in my short time there and help steer this great club back in the right direction.
"I wish all concerned at Widnes Vikings well for the future."