The bitter rivalry between the NRL’s oldest clubs has been further stoked after the Sydney Roosters announced the signing of teenage star Joseph Suaalii.

Rugby league’s foundation clubs had been locked in a battle for the signature of the 17-year-old before the Roosters won out against neighbours South Sydney, landing him on a two-year deal starting immediately.

His release from the Rabbitohs followed months of speculation about Suaalii’s future and was marked by a curt, one-sentence statement.

“The South Sydney Rabbitohs have released Joseph Suaalii from the remaining year of his playing contract following the payment of a non-disclosed transfer fee by another NRL club,” it read.

The transfer of the former Australian Schoolboys Sevens star adds another layer to the frosty relationship between the clubs.

He will join former Souths players Angus Crichton and Luke Keary at the Roosters.

The contract tussle has made the talented outside back one of the most-hyped young players in recent history.

Other NRL clubs also tried to secure him, while Rugby Australia launched an audacious bid to lure him back to the 15-man code he played at The Kings School.

However, after speaking to Roosters coach Trent Robinson, Suaalii opted to join them and he is expected to start pre-season training this week.

He can play wing or fullback, but it’s unknown where he fits into Robinson’s plans.

“Joseph is a highly-talented young player, and we’re thrilled to have secured his services,” said Roosters recruitment boss Daniel Anderson.

“This is a terrific opportunity for Joseph to continue his development alongside the established players we have at the club like James Tedesco, Daniel Tupou and Joseph Manu, and we’re looking forward to watching his progress over the next few years.”

Under NRL rules he is unable to play first grade until he turns 18, which is not until August next year.

However, the Roosters are believed to have made inquiries with the governing body about gaining an exemption for Suaalii to play NRL earlier next season.

But should a request be denied, Suaalii’s first eligible NRL match after his August 1 birthday will be round 21 against Penrith.