Jefferson hit a top score of 222 at Hampshire in 2004

The 6ft 10ins 26-year-old, who severed a tendon in a domestic accident in March, has failed to cement a regular place and has been allowed to move on.

"My opportunities have been limited," said Jefferson, who made 4,300 first-class runs for the county.

"With the progress of others I feel the best chance of furthering my career in the game lies elsewhere."

Jefferson, a graduate of the Durham University centre of cricketing excellence, made his Essex debut in 2000 and was capped in 2002.

He made a total of 11 centuries, and his most productive season came in 2004 when he hit 1,555 runs. In the one-day game he compiled 2,303 one-day runs, including four hundreds.

Essex chief executive David East told the club's website: "It is always very disappointing when we lose players, particularly those who have been part of our development system for many years.

"Will has been a great asset but we fully understand his reasoning and respect the decision he has made.

"We think it is in his best interests to make a clean break now so that he can fully investigate alternative cricket opportunities whilst the season is ongoing."