A fourth British victim of the Algerian siege was named today as efforts continued to repatriate their bodies.
Six UK nationals are thought to have died in the terror attack at the In Amenas plant.
The Foreign Office issued a statement from the family of Sebastian John which said he would be eternally missed.
There was no immediate information on where Mr John lived.
His wife Nicola John said: "Sebastian was the most amazing person. He was a fantastic husband, father, son and brother. There won't be a moment that goes by where we won't think of him.
"We are so proud of Sebastian for all he achieved in his life. He was taken away from us too early and in the most tragic circumstances.
"We will always love him, he will be forever in our hearts and eternally missed.
"Please respect our privacy at this difficult time."
A total of 37 foreign workers are believed to have died at the remote desert facility - part-operated by BP - which was overrun by heavily-armed terrorists.
Some 29 of the hostage-takers died, while three were captured by Algerian troops during a special forces mission to end the four-day stand-off.
Three of the Britons killed have been named as 46-year-old security expert Paul Morgan, systems supervisor Garry Barlow, 49, from Liverpool, and 59-year-old planning manager Kenneth Whiteside, from Glenrothes, Fife.
Colombian BP executive Carlos Estrada, who lived in London, is also believed to have died.
The family of a British survivor said today they were overjoyed that he is safe and well, but need time to come to terms with what has happened.
In a statement issued through the Foreign Office, Lou Fear's loved ones said: "The family is greatly relieved by Lou's safe return.
"This has been a very traumatic experience for the whole family, especially Lou. Our thoughts are with Lou's colleagues and their families.
"We now need to start the process of coming to terms with what has happened and need time alone to do this. We therefore ask that the media respect our privacy."
The Foreign Office refused to confirm any further details but, according to reports in the Daily Mail, Mr Fear, 56, who reportedly lives in Louth, Lincolnshire, and was working as a team leader for BP, hid when the raid on the refinery began, then walked for 20 hours to reach safety.
Another Briton reported to have died in the siege is Carson Bilsland, from Perthshire.
He had reportedly worked in Algeria for around two years as a testing technician and was a former member of the British speed ski team.
The Government is considering increasing logistical support for the French-led military campaign against rebels in neighbouring Mali.
Prime Minister David Cameron has insisted the UK is "not seeking a combat role", but armed forces units have reportedly been placed on "high readiness" to deploy.
Mr Cameron has said there will be a global "generational struggle" against al Qaida-inspired Islamist terrorism in North Africa.
He pledged to provide intelligence and counter-terrorism assets to help track down and dismantle the terror network responsible for the attack in Algeria.
BP group chief executive Bob Dudley has said the company "feared the worst" for four of its 18 employees who have not been found safe.
"We have been gravely concerned for these colleagues and feared one or more fatalities among their number," he said.
"It is with great sadness that I now have to say that we fear the worst for them all. We are doing all we can to support their families and ask everyone to show them consideration and to respect their privacy."
Forensic experts from the UK, US and Norway are working with the Algerian authorities formally to identify a number of bodies found at the site.
A spokesman for the independent Norwich School, where Mr John was an Arkwright scholar, confirmed he attended between 1997 and 2004.
He then went to Loughborough University where he achieved a first class honours degree in civil engineering in 2009. It is understood that he lived in the Nottingham area since leaving university.
A former president of the Institution of Civil Engineers, Richard Coackley, paid tribute to Mr John, saying: "Sebastian was a talented young civil engineer with the world at his feet.
"His mild-mannered, supportive nature made him a pleasure to be around and his commitment and passion for his work and his young family shone through in all that he did.
"It was an absolute honour and a pleasure to have him as my apprentice last year and I know he will be greatly missed by all.
"I join everyone in mourning with Sebastian's family and friends for the tragic loss of a great young man and civil engineer."