French Polynesia's pro-independence leader Oscar Temaru has lost his seat in the territorial assembly.
France's top administrative court ruled that his campaign accounts for the May election were deficient and declared him ineligible for the seat for one year.
It upheld last August's findings of the French national commission vetting campaign contributions which said an entry of $US36,000 was not explained properly.
Last week Mr Temaru's Tavini Huiraatira party said it had been advised by experts that despite some irregularities he would not be declared ineligible.
It said clarifications were submitted, but the court now says no documentation explaining the entry has been presented.
The Tavini campaigned on the issue of probity as the rival Tapura Huiraatira party fielded many candidates with corruption convictions, including the president Edouard Fritch.
Mr Temaru has been French Polynesia's president five times and the president of the territorial assembly twice.
He has also been the mayor of Faa'a since 1983.