Controversy is growing in France over whether secret agents were involved in a failed attempt to rescue French-Colombian hostage Ingrid Betancourt.
The mysterious French plane stayed in Manaus for several days
France has been trying to secure the release of the former Colombian presidential candidate since her abduction by left-wing rebels in February 2002.
The row flared up earlier this week, when a Brazilian newspaper revealed that France in early July secretly sent a military plane to Brazil to collect Ms Betancourt in the event of her release.
The French Government says it only despatched a medical team at the request of relatives, in case Ms Betancourt was released in poor health - but the French newspaper Le Monde on Friday said military intelligence agents were also involved.
Rumours of Ms Betancourt's possible release surfaced in early July, when her sister received a message that the Revolutionary Armed Forces of Colombia (FARC) might be willing to free her on health grounds at the Brazil-Colombia border.
Le Monde - quoting no named source - says a French Hercules C-130 military plane landed at Manaus airport, in the Amazon region of northern Brazil, on 9 July.
Besides doctors, the paper says, the 11-strong party included members of the French foreign intelligence service (DGSE) and a senior aide to French Foreign Minister Dominique de Villepin.
The team also included a "protection team" with "ultra-sophisticated communications equipment allowing them to find their way through the jungle," the paper said.
It is unclear whether Betancourt is still alive
The French authorities have so far insisted that the mission was purely humanitarian, and declined to comment on the latest allegations.
But whatever the nature of the mission to Manaus, the French informed neither the Brazilian nor the Colombian authorities.
Le Monde says that Brazilian officials who tried to board the plane were denied access, with the French claiming diplomatic immunity.
Eventually the French party was asked to leave the country, and Ms Betancourt was never released.
The French Government has categorically denied reports that it has been involved in secret negotiations with FARC.
Brazilian Foreign Affairs Minister Celso Amorim reaffirmed on Friday that his government "had not been consulted" by the French.
The BBC's Jeremy McDermott in Bogota says Colombia has not kicked up a fuss publicly - but adds that privately a senior official expressed anger at the French for not informing the Colombian authorities.
Our correspondent says Ms Betancourt is one of the prize political hostages held by the FARC - along with three US intelligence operatives kidnapped when their plane crashed in rebel territory.
The FARC have said these political hostages will only be released in exchange for imprisoned guerrillas.
Ms Betancourt, 42, has dual French and Colombian citizenship.
Her family has not received any evidence that she is still alive since May 2002.