RARELY have I encountered a more barren, inhospitable ­landscape than that of the ­Sahel-Sahara region of Niger.

It was last year when I visited this West African nation which has become one of the latest operational arenas for the al Qaeda franchise. So desperate is the struggle to find food for many ordinary people unlucky enough to live there that it is not unknown for them to break down termite nests where the insects store tiny amounts of grain. From this, hungry people grind it into a paste which they eat to stay alive in times of severe drought.

I mention this only to give some idea of the harsh climate and environment endured by the four French hostages released this week after three years in captivity at the hands of al Qaeda in the Islamic Maghreb (AQIM), the North African wing of the terrorist organisation.

It was back in 2010 that the men were kidnapped from the Areva uranium mining facility in the Agadez region of Niger. The kidnapping was in line with the behaviour of AQIM, which has targeted French citizens, other westerners and citizens of African countries over the years.

But no sooner were the four hostages freed this week than a storm of controversy brewed up with claims a £21 million ransom had been paid by France's external intelligence service.

The whole issue of paying a ransom for hostages held by terrorists has always been a contentious one.

As far as the hostages' families are concerned - as was evident from the emotional reunion of the Frenchmen - no amount of money is too great to secure the freedom of loved ones.

Viewed from a political and counter-terrorism perspective, however, many would argue ransom payments only help finance and effectively encourage other abductions.

In this latest case, French Foreign Minister Laurent Fabius insisted his government had not paid a ransom. He was, however, vague about whether money had changed hands.

He said: "As far as the French state is concerned, no ransom was paid." When asked if private money had been used, he said "no public money was used".

This might suggest a payment could have come from the hostages' employer Areva or the company's kidnapping and recovery insurance agency. France, unlike Britain, has not gone as far as outlawing ransom payments by companies.

Whatever the source of the cash, there is no doubt the French government has form when it comes to ransom payments. French nationals held in Beirut in the past were released after money changed hands.

If a ransom was paid in this latest case, it flies in the face of an announcement made by French President Francois Hollande earlier this year. Then, as French troops began a military intervention in Mali - which neighbours Niger - to counter AQIM, Mr Hollande promised his government would no longer pay ransoms for hostages.

He also agreed to a British initiative to enshrine a commitment not to pay in the communique of the Group of Eight leaders' summit at Loch Earn, Northern Ireland, in June.

Britain has always argued it is less vulnerable to hostage-taking because of its credible refusal to pay. Critics, however, point to the fact British hostages are frequently killed by their captors.

Whatever Mr Hollande's motive, the release of his four countrymen gave him a substantial political boost just a day after a poll showed he had become the most unpopular French president on record.

Anger with the Socialist leader has hit a new high in France over high unemployment levels, tax hikes and rows over the government's immigration policy.

If we accept the premise that money in this latest case was made available, it is worth pausing to consider how the French deal with AQIM was reached and to what extent the terrorists benefited.

According to a report in the Paris-based Le Monde newspaper, it was France's external intelligence agency that organised the handover of the cash.

There are also reports an immunity deal was struck with Iyad ag Ghali, a Malian Tuareg and leader of the Ansar Dine militant group, in exchange for his help facilitating the release.

According to the US-based independent intelligence monitoring group Stratfor, Mr Ghali has served as a hostage negotiator before. He also has close relations with AQIM, since Ansar Dine fought alongside the Islamists for control of northern Mali in 2011 and 2012.

Analysts point to the fact that, since both sides in the hostage negotiations would have avoided direct contact and electronic communications with each other, Nigerian and Malian mediators might have pressured Mr Ghali to reach out to the Islamists and Mr Ghali may have received an immunity deal in return.

Al Qaeda's men, not known for their altruism, would doubtless not have been motivated simply by a desire to help Mr Ghali, ally though he and his Ansar Dine group had been. Money, pure and simple, was what most likely made AQIM agree a deal with the French.

AQIM has a long track record of extorting ransom payments but kidnapping is not the group's only for-profit activity. The terrorists have a considerable trade in human trafficking and contraband - including cocaine, cigarettes and stolen fuel.

If around £21m was indeed paid for the four French hostages, it would be in line with previous ransom payments made to AQIM. Back in July 2012 the Islamist militants received an estimated £12m to release three aid workers kidnapped in southern Algeria.

According to some intelligence analysts that would have been enough to fund the group through until at least May 2013.

Western and regional security officials say kidnapping has allowed AQIM to buy food, fuel, weapons and favour among the local population and armed groups like Ansar Dine in Mali.

Other wings of the al Qaeda franchise likewise benefit. In Nigeria, Islamist sect Boko Haram was paid around £1.7m by French and Cameroonian negotiators before freeing seven French hostages in April, according to a confidential Nigerian government report.

"Everyone pays, even the British," insists Eric Denece, the head of France's CF2R intelligence think tank. Ransoms, exchanges or force are ultimately the only ways to free hostages, he was quoted as saying.

Arriving home in France on Wednesday bearded and looking gaunt, Thierry Dol, one of the four released Frenchmen, summed up in a brief interview what he and his colleagues had experienced.

"It was difficult, the ordeal of a lifetime," he said. As I write this, many more hostages are enduring similar hardships in West Africa and elsewhere.

One can only hope they too will soon gain their freedom, with or without ransom payments.