LONDON, Aug 28 (Reuters) - Britain's last military flight left Kabul late on Saturday after evacuating more than 15,000 people in the two weeks since the Taliban took control of Afghanistan, ending nearly 20 years of British military presence in the country.

"The final flight carrying UK Armed Forces personnel has left Kabul," Britain's Ministry of Defence said.

Britain on Friday had said its evacuation mission would end within hours and that its military would be unable to fly out any Afghan citizens eligible for resettlement who had not already entered Kabul airport.

"We should be proud of our armed forces, welcoming to those coming for a better life and sad for those left behind," Defence Minister Ben Wallace said after the final British flight.

Britain was at Washington's side from the start of the U.S.-led invasion of Afghanistan that overthrew the then-ruling Taliban in punishment for harbouring the al Qaeda militants behind the Sept. 11, 2001, attacks. More than 450 British armed forces personnel died during two decades of deployment in the country.

President Joe Biden has set an Aug. 31 deadline for the U.S. military to leave Afghanistan, while allied forces including Britain have chosen to leave before then. Britain has also suspended embassy operations in Afghanistan.

Wallace estimated on Friday that between 800 and 1,100 Afghans who had worked with Britain and were eligible for resettlement would not make it out by air, and pledged to help them if they could leave by land.