One Yemeni prisoner at Guantanamo Bay says it is an agonizing, cruel punishment that he would not wish on anyone.

US federal Judge Gladys Kessler describes it as a "painful, humiliating and degrading process."

But for staff at the controversial US military jail, the criticisms of feeding by tubes -- force-feeding or enteral feeding depending on where you stand -- are overblown.

A six-month mass hunger strike by detainees at Guantanamo this year has forced prison authorities to repeatedly resort to the practice to prevent inmates starving to death.

But while it has been decried by a legion of rights groups as inhumane, Guantanamo officials insist it is merely "uncomfortable."

In a tour arranged for reporters last week, journalists were given a glimpse of the protocols governing feeding by tube.

Reporters were shown where hunger-strikers are restrained before a tube delivering essential nutrients is inserted into their body for "feeding."

"For enteral feeding, the first thing we do is offer the person a regular meal," said a hospital medic given the alias "Leonato."

"They refuse that, we now offer a nutritional supplement to drink themselves. "They refuse that, then they're taken by the guards to the enteral feed chair and restrained. We measure the correct length of the tube, they're offered either a (anesthetic) gel or olive oil. The feed lasts 30-35 minutes."

One of Leonato's colleagues, identified only as "Froth", says the procedure is "a quick process."

"The most irritation is when it passes back to your throat," he said. "It's a quick in-and-out process. You do feel it, but it's not painful."

Another colleague agreed. "It just feels uncomfortable."

No journalist was allowed to view an inmate being fed by tube. The sessions are typically conducted twice a day on the 38 detainees who are on the enteral feeding list, out of the 53 who remain on hunger strike.

For the past six months, men scooped up in the aftermath of the September 11 attacks in 2001, and held in Guantanamo without trial for a decade, have been protesting their continued incarceration at the facility.

"Obviously if the men were not eating for six months none of them would be alive," says Guantanamo's head of public affairs Captain Robert Durand.

"We preserve human life on solid legal and ethical grounds," referring to "enteral feeding" rather than "force-feeding."

"Most of them are compliant...it's a process designed to be pain free," Durand added, rejecting judge Kessler's characterization of the practice.

"It's not the dramatic thing you might have seen with the musician's video," Durand said, dismissing a recent video by rapper Mos Def in which he pretended he was being force fed by tubes in violent, disturbing terms.

There is, though, a vast gulf between the official line expressed by Guantanamo officials and testimony by individuals who have experienced the technique.

"There was agony in my chest, throat and stomach," detainee Samir Naji al-Hasan Moqbel told the New York Times. "I had never experienced such pain before. I would not wish this cruel punishment upon anyone."

Four other detainees refer to the practice as "torture", and have called in vain for an end to the practice.

The senior medical officer at Guantanamo however insists feeding by tube is done to "preserve life."

"It's not something that we take lightly," he explains, saying the procedures at Guantanamo are similar to those used in US federal prisons.

The doctor, who withheld his name, had treated the majority of the 106 prisoners from a total population of 166 who had been on hunger strike at the peak this year.

No fewer than 137 medical personnel work at the prison, including 37 drafted in as reinforcements after the hunger strike began.

The doctor admits he sometimes fears for the life of some patients.

"I have (feared for them) because of prolonged hunger-striking," he said. "We'd had quite a few taken to the hospital...we've resuscitated them."

While none of the hunger-striking detainees has ever been declared to be in "danger" the doctor refused to rule out the possibility of a sudden death from hunger-striking, citing "long-term risks."

The trigger for nasal feeding comes when an inmate loses 15 percent of his bodyweight after 21 days of consecutive fasting while exhibiting signs of malnourishment. At that point inmates are fed by tube either willingly or by force.

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