London, Aug 29 (IANS): The final evacuation flight purely for civilians under Britain's Operation Pitting has left the Kabul airport, the British Ministry of Defense said on Saturday.

Any further flights leaving Kabul under Britain's evacuation operation "will have UK diplomatic and military personnel on board," the ministry added.

General Nick Carter, Britain's chief of defense staff, said: "(The withdrawal) is not how we hoped it would end", the Xinhua news agency reported.

"I think we have done an extraordinary job to evacuate as many as we can, but I'm afraid it's absolutely heart-breaking we can't get everybody out," Carter said.

He warned that Britain is "not out of the woods yet" as this final phase gets under way.

"The operation will carry on for a little bit longer. But it's been a huge enterprise," he said, noting that troops are working in the face of a "very demanding threat" in Afghanistan.

Two suicide bomb attacks rocked the Kabul airport in the Afghan capital on Thursday, killing at least 103 people, including 13 US service members, two British nationals and a child of another British national.

The Islamic State has claimed responsibility for the deadly attack, saying it was targeting "translators and collaborators with the American army."

Britain had airlifted 14,543 Afghans and British nationals from Kabul since its Operation Pitting began on August 13, the ministry of defense said on Friday night.

Only three days remain for US-led forces to evacuate from the Taliban-held Afghanistan, after US allies failed to persuade US President Joe Biden to extend the August 31 evacuation deadline during a Group of Seven virtual summit earlier this week.