Farrell includes uncapped quartet in Ireland World Cup training squad

Munster wing Calvin Nash, Leinster backs Ciaran Frawley and Jamie Osborne and Ulster hooker Tom Stewart were all included.

But Leinster back Jordan Larmour and Munster fly-half Joey Carbery have missed out on an initial block of training that starts on June 18.

Ireland, this season's Six Nations Grand Slam champions, have World Cup warm-up games against Italy, England and Samoa in August.

The number-one-ranked side in the world begin the tournament proper against Romania in Bordeaux on September 9. Ireland are still to get beyond the quarter-finals of a World Cup.

A warm-weather training camp in Portugal is also planned for August before Farrell, the father of England star Owen Farrell, confirms his 33-man World Cup squad.

"It is exciting to announce our extended training squad for the first phase of Rugby World Cup preparations, and we are looking forward to assembling in Dublin next month to hit the ground running as a group," Farrell said in a statement.

"It is pleasing to see that selection has been as tough as ever, as real quality players have initially been unfortunate to have missed out."

The former England dual-code international added: "I am sure that camp will be competitive enough as we grow minds and bodies and look to push on with our game from last season.

"In the meantime, it's important that we freshen up for a busy and exciting summer ahead so we are ready to get to work on June 18."