The Hampshire chief executive, Tony Baker, said: "With the county's move to a new ground next season, this is a wonderful way to emphasise the extent of our ambitions going into the new millennium."
The deal is subject to the approval of the Australian Cricket Board, although it has given its blessing to Warne's international team-mate, Glenn McGrath, to play for Worcestershire.
The deals could mean two of the world's top bowlers playing in the Second Division of next year's two-tier County Championship. Worcestershire are already condemned to finishing in the bottom nine of the current competition and Hampshire need to beat Derbyshire in the final round of matches to clinch a First Division place.
McGrath's two-year contract is reported to be worth about pounds 100,000 a season and Warne's deal is set to eclipse that. Hampshire say they expect to meet the cost of his financial package through a number of commercial opportunities together with an increase in gates and membership.
Warne, 30 this week, is captaining the Australians on their tour of Sri Lanka in the absence of Steve Waugh, who has a broken nose. He has taken more than 300 wickets in Test cricket and over 200 in one-day internationals.
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