Jones joins Wales' Six Nations squad for the first time

Uncapped Jones, 26, was last involved with Wales on the 2001 tour to Japan and has been brought in after back row Thomas aggravated a hamstring injury.

Said Wales coach Mike Ruddock: "We've been impressed by his performances at regional level. Over the last months he's come on in leaps and bounds.

"He's started to fulfil his potential and is moving in the right direction."

Thomas suffered a recurrence of his hamstring injury in Ospreys' Heineken Cup loss to Stade Francais on Friday and is doubtful for Wales' Six Nations opener with England on 4 February.

He will have a scan this week to determine the extent of the problem and his likely recovery time.

We've every confidence that he has the ability to meet the challenge of international rugby Wales coach Mike Ruddock on Adam Jones

The 23-year-old has won most of his 22 caps as a flanker, but his 6ft 5in frame also gave Ruddock another option at second row.

So with only two recognised locks in the squad - Rob Sidoli and Ian Gough - Ruddock has opted for Jones instead of another back rower.

"Jones had a particularly good game against Leinster in the Celtic League recently, competing well against a top lineout containing the likes of Malcolm O'Kelly," added Ruddock.

"We feel we need cover in his position with the injury to Jonathan and Ian Evans already ruled out through suspension.

"We have every confidence that he has the ability to meet the challenge of international rugby if called upon."

Ruddock has already lost Grand Slam winners Ryan Jones, Brent Cockbain, Tom Shanklin and Kevin Morgan to injury.

He is also without Gavin Henson and Evans for the first two Six Nations games, while inspirational captain Gareth Thomas is struggling with a knee injury.