David Cameron has heralded the start of a decades-long struggle against Islamist terrorism in north Africa in the wake of the violent climax to the Algerian hostage crisis.
The Prime Minister disclosed that three British nationals were now known to have died and three more were feared dead after the four-day stand-off in the desert. A UK resident is also believed to have been killed.
As Algerian forces continued dismantling the mines and explosives left by the militants who booby-trapped the sprawling BP gas plant at In Amenas, the Algerian authorities warned that the provisional death toll of 23 hostages was likely to rise.
All 32 militants involved in the attack were reported to have been killed - some of them after reportedly "executing" their foreign captives as Algerian special forces mounted their "final assault" yesterday to take back the facility.
Mr Cameron said the attack was a "stark reminder" of the continuing terrorist threat and vowed to use Britain's chairmanship of the G8 to ensure that it was right at the top of the international agenda.
"This is a global threat and it will require a global response. It will require a response that is about years, even decades, rather than months," he said.
"It requires a response that is patient and painstaking, that is tough but also intelligent, but above all has an absolutely iron resolve and that is what we will deliver over these coming years.
"What we face is an extremist, Islamist, al Qaida-linked terrorist group. Just as we had to deal with that in Pakistan and in Afghanistan so the world needs to come together to deal with this threat in north Africa.
"It is linked to al Qaida, it wants to destroy our way of life, it believes in killing as many people as it can. We need to work with others to defeat the terrorists and to close down the ungoverned spaces where they thrive with all the means that we have."
Foreign Secretary William Hague said that 22 British nationals at the plant who survived the attack had been flown back to the UK overnight in aircraft chartered by BP and the Foreign Office.