Sam Burgess & Chris Ashton in England World Cup training squad

Bath's rugby league convert Sam Burgess has been named in England's 50-man World Cup training squad.

Saracens wing Chris Ashton, 28, is given a chance to impress having missed out on the last two Six Nations.

Saracens forward Maro Itoje, 20, is included following an impressive debut Premiership season, along with fellow uncapped players Henry Slade, Luke Cowan-Dickie and Elliot Daly.

But France-based pair Steffon Armitage and Nick Abendanon miss out.

After starting his union career in the centre Sam Burgess (right) has recently moved to the Bath back row

Under Rugby Football Union rules, head coach Lancaster is only allowed to select overseas-based players in "exceptional circumstances", such as an extreme injury list.

"The policy is in place to protect the national team. We've not wavered on it," said Lancaster. "If it changes, more and more people will go to France.

"It's been a difficult decision but the right one."

Abendanon told Sky Sports: "I was really hopeful that he (Lancaster) might make the leap of faith and bring us in, so I am a bit gutted at the decision that's been made."

England's final 31-man squad is scheduled to be confirmed on 31 August, with their World Cup campaign starting against Fiji on 18 September at Twickenham.

Burgess, 26, makes the England squad after only six months in the 15-man game having joined Bath in 2014 from Australian rugby league side South Sydney Rabbitohs.

However, it is not yet clear whether he will be used at inside centre or in the back row, where he has played for Bath in recent weeks having started in the centres.

Also rejoining Ashton in the squad is fellow Sarries wing David Strettle - the pair have scored 20 Premiership tries between them this season.

Ashton, joint-top try scorer at the 2011 World Cup, was last capped during the 2014 summer tour to New Zealand while Strettle is involved for the first time since June 2013.

Their team-mate Itoje, who can play in the second row and the back row, captained England to the Junior World Championship title in 2014 and has made 13 Premiership appearances this term.

Northampton's Calum Clark and Leicester's Ed Slater bring the tally of uncapped players to seven.

Lock Slater returns to the squad following a long-term knee injury, while Joe Launchbury, David Wilson and Ben Morgan are also included following lengthy periods on the sidelines.

Ben Foden, Joe Simpson and Tom Croft have not been included at this stage as they recover from injury but it is hoped they will come into consideration nearer the tournament.

England 50-man training squad:

Forwards: Dave Attwood (Bath), Kieran Brookes (Newcastle Falcons), Calum Clark (Northampton Saints), Dan Cole (Leicester Tigers), Alex Corbisiero (Northampton Saints), Luke Cowan-Dickie (Exeter Chiefs), Nick Easter (Harlequins), Dylan Hartley (Northampton Saints), James Haskell (Wasps), Maro Itoje (Saracens), Courtney Lawes (Northampton Saints), Joe Launchbury (Wasps), George Kruis (Saracens), Matt Kvesic (Gloucester), Joe Marler (Harlequins), Ben Morgan (Gloucester), Matt Mullan (Wasps), Geoff Parling (Leicester Tigers), Chris Robshaw (Harlequins), Ed Slater (Leicester Tigers), Mako Vunipola (Saracens), Billy Vunipola (Saracens), Rob Webber (Bath), David Wilson (Bath), Tom Wood (Northampton Saints), Tom Youngs (Leicester).

Backs: Chris Ashton (Saracens), Brad Barritt (Saracens), Mike Brown (Harlequins), Luther Burrell (Northampton Saints), Sam Burgess (Bath - can also play in the forwards), Danny Care (Harlequins), Danny Cipriani (Sale), Elliot Daly (Wasps), Lee Dickson (Northampton Saints), Kyle Eastmond (Bath), Owen Farrell (Saracens), George Ford (Bath), Alex Goode (Saracens), Jonathan Joseph (Bath), Jonny May (Gloucester), Stephen Myler (Northampton Saints), Jack Nowell (Exeter Chiefs), Henry Slade (Exeter Chiefs), David Strettle (Saracens), Billy Twelvetrees (Gloucester), Anthony Watson (Bath), Richard Wigglesworth (Saracens), Marland Yarde (Harlequins), Ben Youngs (Leicester).