A club statement said: "Gloucester Rugby can confirm the offer, in light of Vickery's injury-plagued career, was designed to spread the risk more evenly between the club and the player."
Wasps, who put the tight-head through a medical this week, will make a decision when the results are known. Vickery, 29, has made just 104 appearances for Gloucester and is in the middle of a period of rehabilitation following the third back operation of his career.
Gloucester's head coach, Dean Ryan, said: "I am disappointed to lose a player of Phil's distinction, leadership qualities and undoubted skill. He has been a talisman for Gloucester for 10 years and his experience was fundamental in our progress."
Vickery, who has 47 England caps, said: "The hardest decision of my life was to leave home at 19 without a career in front of me. I was lucky enough that Gloucester became my home. The decision to leave the club now is the second hardest of my life.
"Gloucester is a place that eats, breaths and sleeps rugby and when you are a player in that environment, it inspires you."
Gloucester face Worcester in today's European Challenge Cup semi-final at Kingsholm with the same team which beat their near neighbours in the Guinness Premiership last week.
"I think last weekend was a big confidence boost for everyone," said Ryan. "I am sure this weekend will be a totally different challenge between Worcester's great set-piece work and our movement and pace."
Newcastle and London Irish meet at Kingston Park tomorrow. Rob Andrew, the Falcons' director of rugby, said: "The implications of this game are massive with a place in a European final and the prospect of Heineken Cup rugby, so we are throwing absolutely everything in to it."
Wasps, who play Leicester at Welford Road in the Premiership today, will be without their Ireland flanker, Johnny O'Connor, for the rest of the season. O'Connor suffered a spinal injuryin the Powergen Cup final a fortnight ago.Reuse content