Bristol-born Tuohy won the last of his 11 Test caps in 2015, while he had spells at Gloucester and Exeter before heading to Ulster.

BREAKING: Ulster lock Dan Tuohy will join Aviva Premiership side @Bristol_RFC with immediate effect. pic.twitter.com/bGmCK8yaU8

— Ulster Rugby (@UlsterRugby) December 6, 2016

Tuohy's arrival at Ashton Gate follows the announcement on Monday that current Connacht boss Pat Lam will take over as Bristol head coach next summer.

Bristol are six points adrift at the Premiership basement, and they face a crunch clash against 11th-placed Worcester on Boxing Day following a two-week break for European action.

"We are pleased to welcome Dan into the fold - he is a formidable presence in the second row and an experienced lineout operator," Bristol's acting head coach Mark Tainton told the club's official website.

"I know Dan well from his time in the Ireland international set-up. His knowledge of the game at the highest level, as well as his leadership skills, will be of significant benefit to the team."

Tuohy added: "When speaking to Mark, it was clear to see the vision he had for the club. I am very excited to have the opportunity to add something to the group.

"I want to thank Ulster Rugby and the IRFU (Irish Rugby Football Union) for the past seven-and-a-half years, and wish them the very best in the future. My attention now turns to helping Bristol retain their place in the Premiership."

Tuohy was due to join up with the Bristol squad on Tuesday as they prepare for Sunday's Challenge Cup tie against French club Pau.