The Union Flag has been lowered in Afghanistan bringing to a close 20 years of British military presence in the country.
The symbolic act means that UK troops have all but withdrawn from the conflict, although Defence sources stressed some personnel remain in Kabul.
Full withdrawal is expected to be concluded imminently.
Italian and German troops left Afghanistan earlier this week, while it is believed US troops will have fully withdrawn by July 4.
The withdrawal of European nations from the war-torn country comes as the US military commander in Afghanistan warned that the country is on the brink of civil war.
Of the 750 British troops that were in Afghanistan, The Telegraph has been told by Defence sources that "most people are out".
It is understood that one of the last flights from the country will be carrying The Black Watch, 3rd Battalion The Royal Regiment of Scotland, back to the UK this week as part of the NATO effort to increase the speed of the withdrawal.
It is understood that the recent ceremonial lowering of the flag took place at Hamid Karzai International Airport.
Robert Clark, a defence fellow at the Henry Jackson Society who served in Afghanistan, said by "striking the flag" it marked the end of the war for the UK.
"It’s a hugely symbolic gesture that the mission is all but over and we can expect a full conclusion within a matter of days now,” he said.
Earlier this year, NATO nations announced that they would withdraw, an act of solidarity with US President Joe Biden, who announced it was "time to end the for ever war" as he pledged to withdraw US troops from Afghanistan by the 20th anniversary of the 9/11 attacks.
However, there has been increasing violence by Taliban militants across the country as foreign troops work towards completion of the withdrawal.
General Austin S. Miller, the US military commander in Afghanistan, said: "A civil war is certainly a path that can be visualized if this continues on the trajectory it’s on right now. That should be of concern to the world."
Meanwhile at a ceremony last week to mark the official end of the Dutch deployment, Dutch Defense Minister Ank Bijleveld-Schouten underscored the uncertain outlook.
"We see reports of the rise of the Taliban, growing violence, also in areas where we were stationed," she said. "A lot has been achieved but we must be realistic: the results are not irreversible."
Tobias Ellwood, chairman of the defence select committee, said: "It’s clear withdrawal plans are being expedited in an attempt to get ahead of any potential Taliban attacks.
"This is far from what success was supposed to look like."
Mr Ellwood added that while UK military forces "performed superbly", the mission lacked "any wider geopolitical strategy".
"It is a stern reminder you cannot win the peace by military means alone," he said. "We are far from out of the woods. Afghanistan is now likely to slide towards a full scale civil war."
It is understood that the UK remains committed to supporting the development of the Afghan National Defence and Security Forces, as they look to become fully self-sufficient, and will endeavour to maintain security for the people of Afghanistan.
A spokesperson for the Ministry of Defence said: “As agreed by NATO Foreign and Defence Ministers, the withdrawal of Resolute Support Mission forces, including those of the UK under Operation Toral, will be complete within a few months.
"The UK is involved in ongoing discussions with US and international allies regarding the future of our support to Afghanistan."