Under ICC regulations, players selected for their country's World Cup squads cannot feature in any other competitions during a period which begins on May 23 and lasts throughout the tournament
Hampshire and the ECB have failed to obtain permission from the ICC to allow James Vince and Liam Dawson to play in Saturday's Royal London One-Day Cup final.
The pair have both been included in England's final World Cup squad and are due to link up with the national squad on Friday, ahead of the weekend warm-up game against Australia.
Under ICC regulations, players selected for their country's World Cup squads cannot feature in any other competitions during a period which begins on May 23 and lasts throughout the tournament.
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It leaves the holders without two of their top performers in the 2019 One-Day Cup for the showpiece match against Somerset at Lord's.
An ECB statement read: "While we understand the ICC decision we are nevertheless disappointed that it will lead to two leading international players missing our showpiece domestic final at Lord's."
However, both the county and the national governing body are to request special dispensation for the pair to feature for Hampshire this weekend.
Dawson has taken 18 wickets at 20.33 in the One-Day Cup this season, in addition to scoring 274 runs at 45.66.
Vince, meanwhile, has made one century and three fifties in his 509 runs at 72.71, with a strike rate in excess of 110.
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