Didier Julia, a 70-year-old member of President Jacques Chirac's ruling UMP party, is expected to defiantly defend his freelance mission when he returns to the French capital on Monday.
He spent four days in the Syrian capital of Damascus overseeing release efforts.
The French government, meanwhile, held an emergency meeting to discuss developments and examine the possible outcome for reporters Georges Malbrunot of Le Figaro newspaper and Christian Chesnot of Radio France International.
The pair were kidnapped south of Baghdad on 20 August along with their Syrian driver. They are believed to be in the hands of a group calling itself the Islamic Army of Iraq.
Julia earned the reprobation of France last Friday when he declared there was a convoy carrying the journalists out of Iraq. Despite the announcement, it failed to materialise.
Julia's assertions revealed inconsistencies and raised questions about the extent the MP might have collaborated with officials from France or other countries.
Chirac's office took the unusual step of saying government authorities "only discovered the reality of the operation run by Mr Julia from Damascus after it had been started", after a report in Le Monde newspaper.
That newspaper suggested the condemnation officials levelled at Julia after the failed mission might have been to cover up government involvement in the operation - possibly by paying a ransom.
"I have done absolutely nothing wrong, nothing obstructive nor
French MP Didier Julia
Over the weekend, Chirac slammed Julia's "interference" while Prime Minister Jean-Pierre Raffarin said such private initiatives could create "a threat for our fellow countrymen".
The opposition Socialist Party's spokesman, Julien Dray, said Julia had probably "not acted as a lone gunslinger" and warned Raffarin would be grilled on the matter in parliament on Tuesday.
Julia said before leaving for Paris via Beirut: "I have done absolutely nothing wrong, nothing obstructive nor dangerous."
He added that he was aware of no other official mission to free the hostages but denied he had some sort of approval from Chirac.
"I did not inform him and was not mandated by anyone for this mission," he said.
The two French journalists were
kidnapped on 20 August
Le Monde published an investigation contradicting his statements and said "several times, the group around MP Julia, financed by the [former French colony] Ivory Coast, entered into contact through unofficial intermediaries with French authorities".
It said Julia left Paris on board a Gulfstream jet owned by Ivory Coast President Laurent Gbagbo on 5 September bound for Jordanian capital Amman.
The newspaper said a shadowy arms dealer, Mustafa Aziz, of Saudi and/or Moroccan nationality and with French residency papers, was also on the flight, "with bags of money", according to one unnamed source.
Le Monde and other newspapers speculated that Gbagbo might have been involved to warm relations with France that have been chilled over the course of a two-year civil war in Ivory Coast, the murder of a French journalist there by a policeman in October last year and the disappearance in April this year of a Franco-Canadian reporter.
Chirac's spokesman, Jerome Bonnafont, rejected the thrust of Le Monde's investigation, saying French officials "never approved, nor backed the personal initiative of Didier Julia and his collaborators".
"All of France's representative figures [should] not get into debates that could undermine the national consensus and, at the same time, have consequences on the liberation of Christian and Georges"
Statement from the families
He added that "much information is being transmitted to French authorities" about the hostages.
Each lead is weighed carefully, he said, but information Julia provided on 27 September about his operation was too "imprecise" to warrant a response.
Chesnot and Malbrunot's families issued a statement on Monday asking "all of France's representative figures to not get into debates that could undermine the national consensus and, at the same time, have consequences on the liberation of Christian and Georges".
They called on "the responsibility and discretion of everybody so that negotiations resume in the necessary calm".