BP employee Alan Wright, 37, was working at the plant in In Amenas on Wednesday when the Islamist terrorists stormed the compound.
The father-of-two hid in an office before he and Algerian colleagues cut a fence and fled. He said: "If you have been captured, there's pretty much no escape."
His account came as First Minister Alex Salmond said two Scots, or people with immediate Scottish family connect-ions, were believed to have been killed. Eight survivors were Scots. Mr Salmond said: "The Scottish authorities continue to offer every support to all caught up in this crisis, and remain in close contact with the UK Government."
The confirmed death toll of 23 hostages was set to rise. Three British nationals were known to have died in the four-day stand-off, and three were thought to be dead. A UK resident was also belie-ved to have been killed.
Algerian bomb squads searching the desert complex for booby-traps left by the terrorists were said to have found 25 bodies.
There there were reports that five had been captured alive.
The 22 Britons who survived the attack were recovering at home having been flown back to the UK in plane chartered by BP and the Foreign Office.
Among them were Iain Strach-an, a 38-year-old electrician from Howwood in Renfrewshire and Mr Wright, of Portsoy, Aberdeenshire, who was working on Wednesday when he thought there had been a power cut.
Word soon spread it was an attack so he and three ex-pats and about a dozen Algerians holed up in an office.
He said, "everyone went into safe mode" and assessed what they were going to do and stocked up on supplies.
The group got a satellite phone, taped up the window and locked the door. Soon after they heard gun fire but could not tell where it was.
THE terrorists had tried to clear the buildings of workers and a jihadist patrolled outside their hideaway, trying to trick them out.
Mr Wright told a broadcaster a man walked past saying 'good morning' in a friendly Arabic voice. "That was the moment we thought we are in big trouble," Mr Wright said.
The group then spent a terrifying nine hours trying to stay out of sight and wondering what was happening.
At 6pm they left the office for another room and the expats grew concerned the Algerians would leave them, as they were free to go, and inadvertently betray their position.
Mr Wright phoned home a few hours later to reassure his family, he said, although he was still in grave danger.
He said he did not want to speak to his two daughters as he did not want his last convers-ation with them to be on a crackly phone. In the morning, despite wanting to stay hidden, Mr Wright went along with a plan the nationals had to flee. He was given a hat to make him "look less expat" and the group, now swollen to about 30, made a break for it.
"The first cut of the fence, the wire and tension makes such a noise when it breaks and you knew it travelled to where the terrorists were," Mr Wright said. "But within 30 seconds they had both fences open and we were free to go."
Mr Wright said it was important not to run and attract attention.
"You know these guys are behind you and if they see you, you don't know if they're going to be shooting at you, you just don't know where everybody is. There was relief, but you've no idea what is out there.
"We got about a kilometre into the desert and you can see the military point with eight or nine military personnel with guns pointing into our spot but also that they had identified us and were comimg our way.
"Then you think 'Is it the terrorists or is it the gendarmes?' For 20 minutes you're not sure. We were on our knees with our hands up."
The group was then split into Algerians and expats and Mr Wright thought they'd walked into the hands of the terrorists.
HE said: "You're thinking you've just made the biggest mistake of your life.
"You just think that's it. You fear the worst, you can't put into words how bad you feel. It's something you never want to go through again."
Mr Wright applauded Algerian colleagues in helping the expats – "the guys had the option to surrender and be safe but decided to stay and help us escape – and thanked the military for helping to save him.
He added that his thoughts were with those killed.