Friends and family members said Fai, 20, was caught in a riptide in dangerous surf near Auckland during a weekend family outing in which he went out to help a younger brother who couldn't swim, The Times of London reported Monday.
Fai's sister, La Lelei, told a New Zealand Web site that he had helped his younger brother to drift into shore at Bethell's Beach but then was taken out to sea by a wave, the Times said.
Rescuers on inflatable boats were joined by family members Sunday, searching the beach for the missing rugby player until 1 a.m. Monday.
Members of the New Zealand Warriors team, which was due to officially begin pre-season training Monday, joined in the search for their missing teammate when rescue activities resumed at dawn Monday, officials said.
Fai, considered a rising star, played 15 games for the Warriors in 2008 after making his debut with the club last March, the Times reported.