Since 1985, the Department of National Parks, Wildlife and Plant Conservation has disputed ownership of 71 rai Poda Island through the courts.
With a Supreme Court ruling in December 2011 that the island must be returned, the final countdown is on in the drawn-out battle.
Chon Bhinkhaolon, a former local Krabi politician and consultant, claimed ownership of the island and erected luxury villas and restaurants there.
The Poda property package is said to be worth one billion baht and to attract about 1000 tourists most days, making it a desirable island to own.
However, Thai media reports, notices have been posted by the Director of the nearby Noppharat Thara National Park, Chaidhat Boonbhuphantapti, giving the present occupants until July 18 to vacate the premises.
Once the deadline passes, National Park authorities will have until August 31 to demolish the construction on the island and restore it to parkland.