Bater joins the Scarlets from rival Welsh region the Ospreys

The Wales pair are the first recruits for new Scarlets boss Phil Davies, who previously coached Thomas in his former role with the Tykes at Headingley.

"These are two very important signings for the club and I am delighted to have secured both players," said Davies.

"Having worked with Nathan at Leeds I know all about his qualities and he will bring a hard, competitive edge."

Former Wales back-rower Thomas, who won the last of his nine Wales caps against South Africa in 1998, had asked to be released by Leeds following their relegation from the Guinness Premiership.

James Bater is one of the brightest young back-row talents in Wales Llanelli Scarlets coach Phil Davies

The 30-year-old, who started his career at home-town club Bridgend, moved to the Tykes from the Cardiff Blues last summer, having previously enjoyed seven years at Bath.

Bater, 26, whose only cap came against Romania in 2003, was available as the Ospreys have Ryan Jones fit again and have signed Kiwi pair Filogia Tiatia and Jono Gibbes.

Bater had an outstanding 2004/5, getting back into the Wales squad, but has been hampered by injury this year.

"James is one of the brightest young back-row talents in Wales," Davies added.

"He has displayed good leadership qualities at his former clubs and surely deserves more than the one Welsh cap he has under his belt to date."

Thomas and Bater will join a pool of back-row talent at Stradey Park that already includes Ireland international Simon Easterby, Wales No 8 Alix Popham and rejuvenated Welsh openside Gavin Thomas.