Leinster moved confidently into the last eight of the new Celtic League with a comfortable 34-18 victory over a woeful Swansea side at St Helen's.

The Irish province ensured a home draw in the quarter-final after finishing their pool unbeaten.

They could even afford to rest the majority of their international stars and still have enough firepower to douse a hugely disappointing home display.

Leinster dominated in all phases and out-scored the home side four tries to none in a match littered with errors.

Wales' international fly-half Arwel Thomas kept his side in the game with six penalties, but Swansea rarely threatened to trouble the visiting line.

Leinster fly-half Nathan Spooner gave the Irish side the lead on four minutes before opposite number Thomas replied with two penalties of his own.

But Leinster soon made their early dominance pay when right-wing Simon Keogh twisted through some flimsy cover defence for Spooner to convert.

Thomas reduced the arrears after 60 minutes. But the home defence, which had previously been so impressive for Swansea this season, crumbled once more as left-wing John McWeeney dived in unopposed for his side's second try.

There was more to come as Leinster full-back Peter McKenna outstripped the despairing grasp of centre Gavin Henson to feed McWeeney on the inside for another simple score.

Things did not look good for Swansea at 24-12, and matters became worse when they saw international lock Andy Moore shown the yellow card just before the break.

Swansea managed to stem the tide after that.

Thomas offered some hope with two more penalties, but Leinster sealed an emphatic triumph with a darting try from lively scrum-half Ben Willis.