French President Francois Hollande  hostage Serge Lazarevic Villacoublay airport Paris.
French President Francois Hollande and former hostage Serge Lazarevic hug each at the Villacoublay military airport, near Paris. Reuters

A Frenchmen who held hostage for more than three years by al-Qaeda's North African branch was released in a prisoner exchange, it has been reported.

Serge Lazarevic was welcomed by France's president Francois Hollande at the Villacoublay airport outside Paris, were he was flown from Niger after he was freed by his Islamist captors.

Hollande expressed "extraordinary joy" at Lazarevic's return and warned his fellow citizens to avoid dangerous areas.

"I want to send a clear, simple message to all our fellow citizens who can be in so-called zones at risk. Make sure not to go where you can get abducted."

Lazarevic was the last of up to 14 French nationals that were held hostage by Islamist militants in northern Africa in recent years.

The 50-year-old was snatched from a hotel in Hombori, north eastern Mali, with his business associate Philippe Verdon who was then shot dead by al-Qaeda in the Islamic Maghreb (Aqim) in March 2012.

Hollande thanked the presidents of Niger and Mali for helping in the release, amid reports that at least two jihadists with al-Qaeda in the Islamic Maghreb were set free to secure Lazarevic's safe return home.

Le Monde newspaper quoted an unnamed Malian security source as saying that Bamako opened prison gates for several Islamist militants, including the mastermind of Lazarevic's abduction, in exchange for the Frenchman.

Aqim members Heiba Ag Acherif and Mohammed Ali Ag Wadossene were let out of their cells in Mali and flown to Niger at the weekend, a Malian prison official confirmed to the BBC.

French cabinet minister Stephane Le Foll told France 2 that he was aware of reports on the alleged prisoner swap, but he couldn't confirm their authenticity.

"I can't comment on things that I don't know," Le Foll said.

The French government has been criticised by some of its western allies over allegations it often paid millions in ransom to Islamist groups to secure the release of its captive citizens.

Paris denies the allegations although, Hollande has acknowledged that other countries have sometimes paid hostage-takers, "to help us".