Players with dual eligibility can switch their international allegiance by participating in Olympic qualifying events provided they had a passport for the second country and have completed a stand down period of three years.
Piutau played the last of his 17 tests for the All Blacks in 2015 and first stated four years ago that he would love to represent his Tongan heritage.
Tonga sevens coach, Tevita Tu'ifua, said after a couple of false starts the signs are promising that a number of former All Blacks and Wallabies stars could pull on the red jersey in June.
