In May, a magistrate had agreed to hear the case, in which campaigners alleged that between them the leaders own 160 million euros (236 million dollars) worth of real estate in France, allegedly paid for with embezzled public funds.

But French state prosecutors refused to take up the case and on Thursday appeals judge Francoise Desset ruled that since Transparency International had not itself lost out it could not make a complaint.

"Today it's champagne all round for the gang of Franco-African crooks that organise and profit from the looting of African public funds," complained Transparency International's lawyer William Bourdon.

Campaigners had hoped to force France to seize luxury homes they allege are owned by presidents Ali Bongo of Gabon, Teodoro Obiang Nguema of Equatorial Guinea and Denis Sassou Nguesso of the Republic of Congo.

Obiang's lawyer Olivier Pardo welcomed the court's ruling which he said "showed that the manipulation of French justice had not worked" and vowed to bring a slander suit against Transparency.

Bongo's counsel, Patrick Maisonneuve, said the ruling showed French-based activists could not pretend to complain on behalf of African taxpayers. "As a jurist, I'm satisfied with this correct application of the law," he said.

Anti-corruption campaigners have identified dozens of properties in France -- 30 in the case of Bongo's family alone -- which they say were paid for by African leaders and their associates with looted funds.

The French government, which maintains close ties and has oil contracts with its former African colonies and some other states on the continent, has resisted calls to investigate.