The Britons were among 30 hostages killed, of whom the nationalities of 15 had been established. Of these, eight were Algerian and seven were foreigners, including the two Britons, two Japanese and a French national.
The wife of a worker currently working at an oil compound in the country said they never envisaged a terrorist attack.
The woman, who did not wish to be named, said: "Before he left this Monday, I joked that whenever I thought of oil compounds the image of a siege by terrorists came to mind. Never in my worst nightmares could I have guessed this could become reality.
"My husband tells me the Algerian employees with him are all very shocked that such an attack could occur in Algeria – it had been a relatively safe country.
"I can't imagine what the families of those affected must be going through. For myself, I will pray until my husband gets home safely."
Two groups, thought to be affiliated to al Qaeda, Katibat Moulathamine, or the Masked Brigade, and another, Signers in Blood, have both claimed responsibility.
The terrorists said the raid had been carried out because of Algeria's decision to allow France to use its airspace for attacks against Islamists in Mali.
UK Foreign Office Minister David Lidlington said the Government has vowed to play its part to counter the creation of a new "terrorist haven" on Europe's doorstep.
The vulnerability of oil and gas infrastructures to various threats – both physical as well as cyber – has caused a rise in security investment.
Analysts Frost & Sullivan say the oil and gas security market earned revenues of $18.31 billion in 2011 worldwide and estimates this will reach $31.27bn by 2021.
Two years ago, 90 British oil workers were evacuated by charter flights after being left stranded in a compound in the deserts of neighbouring Libya as it was on the brink of civil war.
El Watan, Algeria's leading independent French-language newspaper, said the hostage-taking "is a timely reminder Algeria was and is still a prime target for terrorist groups acting within and outside our borders".
The paper said anyone who thought the country "benefited from any temporary respite in the eyes of the extremists" due to Algiers' response to France's intervention in Mali, which favoured a negotiated political settlement, has been roundly disabused.
An attack on the personnel of a foreign company from a country – Britain – which is participating in the Mali conflict with transport aircraft and logistical support, establishes a firm link to the fighting across Algeria's southern border, it said.
Meanwhile, former hostage Stephen McFaul, 36, of Belfast, made contact with his wife Angela around 3pm yesterday to say he was safe and well.
One of his two children, 13-year-old son Dylan, choked back tears as he declared he would give the electrician a "big hug" as soon as he sees him and never let him go overseas again. "I am very happy, I just cannot wait for him to come home," he said.
Mr McFaul, who also has a four-year-old son, Jake, is being looked after by Algerian authorities while arrangements are made for his return.