Tonga are in a tough group which also contains England, France, Argentina and the United States.

Only the top two will advance to the knockout rounds although the third-placed team in each group will earn an automatic berth for the next World Cup in 2023, but Kefu, who won the World Cup with Australia in 1999, said that would not be enough.

"I'm fixated on making the playoffs," he said at the squad announcement in Hamilton, where Tonga are preparing for their final warm-up match against New Zealand on Saturday.

Tonga lost 29-19 to Fiji in Auckland on Saturday.

"Our squad is comprised of players who play in some of the top competitions around the world including the English Premiership, the Top 14 and Super Rugby," said Kefu.

Tonga open their World Cup against England on September 22 and then play Argentina and France before concluding their campaign against USA on October 13.

Forwards: Siegried Fisi'ihoi (Pau/FRA), Vunipola Fifita (Brumbies/AUS), Latu Talakai (Eastwood/AUS), Paula Ngauamo (Agen/FRA), Sosefo Sakalia (Bucarest/ROM), Siula Maile (Shirley/NZL), Siua Halanukonuka (Glasgow/SCO), Ma'afu Fia (Ospreys/WAL), Ben Tameifuna (Racing 92/FRA), Sam Lousi (Scarlets/WAL), Leva Fifita (Grenoble/FRA), Steve Mafi (London Irish/ENG), Sione Kalamafoni (Leicester/ENG), Mamaa Vaipulu (Castres/FRA), Fotu Lokotui (Counties Manukau/NZL), Zane Kapeli (Bay of Plenty/NZL), Dan Faleafa (Coventry/ENG), Nasi Manu (Benetton Treviso/ITA)

Backs: Sonatane Takulua (Newcastle/ENG), Leon Fukofuka (Auckland/NZL), Samisoni Fisilau (sans club), Kurt Morath (Doncaster/ENG/D2), James Faiva (El Salvador/ESP), Siale Piutau (Bristol/ENG), Malietoa Hingano (Bayonne/FRA), Nafi Tuitavake (no club), Atieli Pakalani (Eastwood/AUS), David Halaifonua (Coventry/ENG), Viliami Lolohea (no club), Cooper Vuna (Newcastle/ENG), Telusa Veainu (Leicester/ENG)