Kadeer batting on the England A tour of India in February

The 21-year-old turned down the offer of a new two-year contract to join the C&G Trophy winners on similar terms.

"I am delighted to be joining a club with such an impressive record and it will no doubt help my cricketing aspirations," he said.

"Obviously, it is sad to be leaving Worcestershire after five years but I feel it is now time for me to move on."

Kadeer, the cousin of Worcestershire and England paceman Kabir Ali, was lined up to open the batting during the 2004 season.

But he missed the beginning of the campaign with an elbow injury, allowing Stephen Moore a chance and the latter went on to score more than 1,000 first-class runs in his first full campaign.

Despite that, Gloucestershire are expecting great things from Kadeer who has played for England under-19s and toured Sri Lanka with the England A team.

"I am excited by having Kadeer Ali in my squad. He has great talent and I intend to create an environment in which he can exploit fully his talent.

"It is important that we continue to develop the squad and manage the transition to the future, and he is a very welcome addition," said player-coach Mark Alleyne.

Kadeer will rejoin former Worcestershire team-mate Phil Weston at Bristol following the latter's switch two years ago.