President Francois Hollande and relatives met the journalists as they arrived home. Photo: BBC

Didier Francois said the four men were chained to each other and kept in basements without natural light.

His colleague Nicolas Henin added that they were "not always well treated".

Mr Henin and Mr Francois, along with Edouard Elias and Pierre Torres, were greeted by their families and President Francois Hollande on arrival in France.

They had been found by Turkish soldiers on the Syrian border late on Friday.

The jihadist group Islamic State of Iraq and the Levant (ISIS) has been accused of kidnapping them.

'Happy to be free'

Television footage after their reappearance in Turkey showed the men looking unkempt, with beards and long hair, but in good health.

They had shaved by the time they arrived at Villacoublay military airport, outside Paris.

Mr Francois, 53, told reporters it was "a great joy and an immense relief, obviously to be free. Under the sky, which we haven't seen for a long time, to breathe the fresh air, walk freely".

"It was a long haul, but we never lost hope," he added. "From time to time, we got snatches of information, we knew that the world was mobilised."

He told his own radio station, Europe 1 that they had spent "six whole months in basements without seeing daylight, and for two-and-a-half months we were chained to each other."

The journalists were found blindfolded and handcuffed in a no-man's land in Turkey's border province of Sanliurfa and were taken by Turkish soldiers to a police station in the nearby town of Akcakale.

The men went missing in two separate incidents last June.

Mr Francois, a veteran war correspondent, and Mr Elias, a photographer, were abducted in early June on their way to Aleppo.

Mr Henin, who was working for Le Point magazine, and Mr Torres, reporting for French-German television channel Arte, were taken later that month near Raqqa.

The journalists (from left to right) Edouard Elias, Didier Francois, Nicolas Henin and Pierre Torres were met by President Hollande and Foreign Minister Fabius

Welcoming them, President Hollande called it a "day of great joy" both for the four journalists and for France.

Chemical weapons use?

Negotiations with their kidnappers had been going on for several weeks but it is not known if anything was offered to them in return for freeing the men, the BBC's Hugh Schofield reports from Paris.

Foreign Minister Laurent Fabius denied a ransom had been paid or that weapons had been delivered to the kidnappers.

He also told Europe 1 that "there was no question of contact with the Syrian government", saying only that the negotiation for their release "was of another nature".

President Hollande told the same radio station that France had "information" but no firm "proof" that the government of Bashar al-Assad was still using chemical weapons on its people.

The Assad regime is currently in the process of handing over all its chemical weapons as part of a US-Russia brokered deal last year after deadly attacks outside Damascus killed hundreds of people.

More than 150,000 people have been killed in the Syrian conflict, with millions forced to flee their homes during more than three years of conflict.

Syria has also become one of the most dangerous places for journalists, with more than 60 killed since the beginning of the uprising against President Assad.