PARIS: Many of them had explosives wrapped around their necks. Others hid, petrified, under their bed, in gaps above ceilings or wherever they could for nearly two days.

The ordeals suffered by workers caught up in the hostage drama at an Algerian gas field began to emerge Friday as the first survivors to make contact with friends and family started to tell their horrifying stories.

"There were gunshots, explosions and an alarm went off," was how an Algerian engineer described the moment, before dawn on Wednesday, when he realised the plant was under attack from Islamist gunmen.

"Just after, everything went dark," he said. "They cut the electricity and started going through the rooms, smashing down doors when they had to."

He said the kidnappers stalked the site looking for foreigners.

"All the time they were shouting that they were only after expats: 'if you're Algerian you can go, get your stuff and get out!'

"They rounded up all the expats, tied them up and took them off."

One of the westerners who escaped the attackers was Alexandre Berceaux, an employee of CIS Catering, the French company responsible for feeding 700 workers on the huge Tiguentourine site located in the desert in Algeria's deep south.

He was in his room getting ready for his morning shift when the alarm went off but initially assumed it was just a routine drill.

He soon realised he couldn't have been more wrong and made a decision that may have saved his life.

Rather than fleeing, Berceaux stayed in his room and hid under his bed, where he remained for 40 hours, praying the gunmen would not find him, before finally being liberated by Algerian troops who stormed the site on Thursday evening.

"I was under the bed and I put boards everywhere just in case," Berceaux said. "I had a bit of food, a bit to drink, I didn't know how long it would last."

When he finally came out, the Frenchman discovered that three Englishmen had survived in similar circumstances having hidden in the space above a dropped ceiling.

Built by Japanese and American companies and operated jointly by Algeria's state oil company, Britain's BP and Norway's Statoil, the Tiguentourine complex had employees from all over the world.

They were the targets of gunmen described by escapees as mostly young, relaxed and heavily-armed and of north African/Arabic appearance but with non-Algerian accents.

Attaching Semtex belts was presumably designed to deter them from trying to escape whilst ensuring any army assault would result in a maximum number of casualties among the foreigners.

One of the victims of these tactics was Stephen McFaul, a 36-year-old electrical engineer from Belfast. He was part of a group which managed to escape when the Algerian army attacked a convoy of vehicles the Islamists were using to try and move to a different location.

McFaul's testimony, related by Irish Foreign Minister Eamon Gilmore, confirmed that of a French hostage who spoke to the France 24 television station by phone on Thursday evening. He described how he was being held in a booby-trapped building along with English, Japanese, Filipino and Malaysian nationals, some of whom had been tied up and fitted with explosives.

McFaul's relieved relatives offered an insight into the agony suffered by family and friends and how, for many of the survivors, this will have been a life-changing experience.

"I can't wait till he gets home. I'm just going to say that he's never going back there, I'm not letting him go back," McFaul's 13-year-old son, Dylan, told Sky News.

His father, Christopher, added: "I feel sorry for the other hostages that are still there. We don't know what's happened to them, and the ones who have been killed -- I feel sorry for their families. The last 48 hours have been hell."