The leaders of the three countries had all denied the charges
A French appeals court has halted a lawsuit against three African leaders accused of embezzlement.
Anti-corruption group Transparency International had accused the leaders of using African public funds to buy luxury homes and cars in France.
But the court ruled the activists could not act against foreign heads of state.
Denis Sassou-Nguesso of Republic of Congo, Teodoro Obiang Nguema of Equatorial Guinea and the late Omar Bongo of Gabon denied any wrongdoing.
The court's ruling was welcomed by lawyers for Mr Nguema, who were quoted by Reuters news agency as saying it showed that "attempts to use the French justice system for obscure purposes are doomed to fail".
A lawyer for President Ali Bongo of Gabon - Mr Bongo's son, who was elected following his father's death earlier this year - said he was "satisfied" by the ruling.
"We are not hostile to the idea of transparency," he told the Associated Press news agency.
The case followed a 2007 French police investigation which found the leaders and their relatives owned homes in upmarket areas of Paris and on the Riviera, along with luxury cars, including Bugattis, Ferraris and Maseratis.
Transparency International, along with rights group Sherpa, had argued that it was not possible that the men and their entourages had bought the assets through their legitimate salaries.
Last May, a French magistrate had ruled that the case, which became known as the "ill-gotten gains" case, was admissible in a French court.
But representatives of the leaders had contested that ruling, saying that as civil society activists, Transparency International had no right to act as plaintiffs against heads of state.
Transparency International said it would appeal against Thursday's ruling.
Police found the leaders owned luxury properties on the French Riviera
"Those in France and Africa who organise and take advantage of the looting of African public money will be celebrating with champagne," said William Bourdon, a lawyer for Transparency International.
The organisation said it regretted what it called the court's "legally questionable" decision to throw out its case.
In a statement, it said the move was "all the more regrettable because it prevents the opening of a case even though there is no doubt that the holdings identified by the police could not have been made solely with the salaries and fees of the targeted heads of state".
The ruling showed that French law "still needs to evolve" to allow groups such as itself to take legal action, it said.
"Without that, we will continue to deprive victims of corruption of an indispensible means to guarantee their rights."
Maud Perdriel-Vaissiere of Sherpa told AP the news was "a big blow" but was "just one step in a legal battle that will be long".
Gabon and Republic of Congo are former French colonies, while Equatorial Guinea is a growing oil exporter.
Omar Bongo - who was Africa's longest-serving leader - died in June, but members of his family were also named in Transparency International's case.