Michael Jennings scored a first-half hat-trick as Tonga hammered Scotland 50-4 in their first game of the Rugby League World Cup, while Lebanon claimed a historic win and Ireland overcame Italy.

Tonga moved above New Zealand to lead the way in Group B, scoring seven of their nine tries in the first half at Barlow Park on Sunday.

Kristian Woolf's side ran riot in Cairns, where Jason Taumalolo, who turned his back on New Zealand to play for Tonga, was outstanding in a one-sided encounter.

Former Australia centre Jennings put the Mate Ma'a in front with an early try and added another following an incisive run from Taumalolo, who helped himself to a four-pointer of his own.

Sika Manu, Daniel Tupou and Peni Terepo added further tries before the clinical Jennings completed his treble to give Tonga a 38-0 lead at the break.

Danny Addy went over from dummy-half to get Scotland on the board early in the second half before Tupou claimed his second and Ata Hingano added try number nine for Tonga, Sio Siua Taukeiaho sailing over his sixth conversion to take his side to the half-century mark.

Lebanon claimed their first ever World Cup victory at Canberra Stadium, seeing off France 29-18.

Mitchell Moses pulled the strings and Travis Robinson claimed a double as the Cedars outscored France by five tries to three to sit second in Group A.

Meanwhile, Liam Kay scored two of Ireland's six tries in a 36-12 defeat of Italy in Cairns.