Double World Cup winner Dan Carter will not rejoin French club Racing 92 due to medical reasons, the club announced on Saturday.

Carter, 36, who starred for the French giants between 2015 and 2018, has been deemed ineligible to play in France by the French National League (LNR) after his former outfit referred his medical results to the organization which runs the Top 14 competition.

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His health dossier was passed to the LNR as part of his registration as a Racing92 squad member—as is the case with every new player in the league.

"Racing 92 handed over certain elements of his medical dossier to the experts designated by the French National League. Their opinion was unanimous: Dan Carter can't play rugby in France," said a statement.

"We are very disappointed of course but... the law is harsh but it is the law and we don't compromise players' health.

"We wish Dan the best for the future, a future at the same level of his immense career."

The former Top 14 champions said last month Carter would return on a short-term deal from Japanese side Kobelco Steelers as cover for ex-South Africa fly-half Pat Lambie, who announced his immediate retirement in January due to numerous concussions.

Other options at fly-half for the millionaire-backed outfit are Scotland's Finn Russell, second-choice Ben Volavola and journeyman Raphael Lagarde.

Carter was expected to supplement the options at stand-off as Racing 92 eye a place in the end-of-season playoffs and a first European Champions Cup with a quarterfinal tie against Toulouse on March 31.

During his previous three-year stint in the French capital, Carter won the league title but failed to lift the European Cup, losing in two finals. He scored 445 points in 58 games.

Before that, he won New Zealand's provincial competition with Canterbury and Super Rugby with the Crusaders.

On the international front, he twice lifted the World Cup, the Tri Nations and the Rugby Championship as well as a British and Irish Lions Test series with the All Blacks.

Carter's last spell in France was tarnished on two occasions.

He tested positive for anti-inflammatory drug corticosteroid in 2016 but was eventually cleared of any wrongdoing in April 2017.

In the same year, he was caught driving while two-times over the legal alcohol limit by French police and subsequently fined 1,000 euros ($1,137).

Carter was set for his third contract in the Top 14, having made only five appearances for Perpignan in 2009 because of an achilles injury.

When it was announced that he was due to return to Racing, club owner Jacky Lorenzetti insisted it was with one mission in mind—to win the European Cup.

"It's the only title he's missing, he added to his collection with Japan's Top League in December so why not become a European champion with us," Lorenzetti said.

"He wanted to come back, we wanted to have him back, we came to an agreement very quickly on financial conditions."

Thomas treble 

However, coach Laurent Travers played down Carter's potential impact on the side.

"He's not Zorro. We've always been happy with what he brings to the team but he's not going to run across the field and ensure we get good possession, but he will help us to build," Travers said.

Despite the Carter setback on Saturday, Racing at least had a victory on the pitch to celebrate with France winger Teddy Thomas scoring a hat-trick of tries in a 50-14 win over La Rochelle at their Defense Arena ground.

Elsewhere, Clermont closed the gap on leaders Toulouse to a point by thumping strugglers Grenoble 52-17.

Springboks Bismarck du Plessis and Francois Steyn scored as Montpellier beat Bordeaux-Begles 37-10 and Pau overcame Agen 27-17 to give Simon Mannix's side some breathing space away from the relegation playoff spot.