LONDON, July 8 (Reuters) - Most British soldiers have been pulled out of Afghanistan, ending Britain"s official role in a two-decades long conflict even as the Taliban are gaining ground and amid fears the departure of foreign soldiers could lead to civil war. "All British troops assigned to NATO"s mission in Afghanistan are now returning home," Prime Minister Boris Johnson told parliament, praising what British forces had achieved while at the same time acknowledging the "perils" facing Afghanistan. "For obvious reasons, I will not disclose the timetable of our departure, though I can tell the house (parliament) that most of our personnel have already left," Johnson said. British forces were first deployed to Afghanistan in 2001 following the Sept. 11 attacks on the United States and played a major role in combat operations until 2014. A total of 457 British soldiers were killed in the country. NATO, of which Britain is a member, said in April that its troops would begin withdrawing in co-ordination with a decision by President Joe Biden to pull U.S. troops out by Sept. 11. read more Violence has raged throughout Afghanistan in the weeks since then. The United States last week abandoned Bagram air base, the longtime staging ground for U.S. military operations in the country, effectively ending America’s longest war. The Pentagon says the withdrawal of U.S. forces is 90% complete. Johnson said he did not underestimate the challenges facing Afghanistan, adding the government would continue to provide development assistance. "I hope no one will leap to the false conclusion that the withdrawal of our forces somehow means the end of Britain"s commitment to Afghanistan, we are not about to turn away, nor are we under any illusions about the perils of today"s situation and what might lie ahead," Johnson said. British Prime Minister Boris Johnson holds a news conference for England"s COVID-19 lockdown easing announcement in London, Britain July 5, 2021. Daniel Leal-Olivas/Pool via REUTERS British Prime Minister Boris Johnson holds a news conference for England"s COVID-19 lockdown easing announcement in London, Britain July 5, 2021. Daniel Leal-Olivas/Pool via REUTERS CIVIL WAR WARNING Britain"s Ministry of Defence said a small number of troops will remain to protect diplomats. Nick Carter, who as Chief of the Defence Staff is the head of the armed forces, said there is the possibility that Afghanistan could be on a path to civil war as American and other foreign troops leave. Recent news from Afghanistan has been "pretty grim" and it is "plausible" that the country"s state would collapse without foreign troops there, he told reporters. Afghanistan could see a situation like the country"s 1990s civil war "where you would see a culture of warlordism and you might see some of the important institutions like security forces fracturing along ethnic, or for that matter, tribal lines," he said. "If that were to happen, I guess the Taliban would control part of the country. But, of course, they would not control all of the country." Johnson said Britain could be proud of its role in Afghanistan. The U.S.-led coalition supported the Northern Alliance in toppling the Taliban government, accused by Washington of harbouring al Qaeda after the militant group carried out the Sept. 11, 2001, attacks on the United States. He said there have been improvements in women"s rights, and education, and there has not been a militant attack in the West launched from Afghanistan since the invasion. "No-one should doubt the gains of the last 20 years, but nor can we shrink from the hard reality of the situation today," he said. "It is true that the Taliban are making rapid progress in rural areas, but that does not mean ... that they are guaranteed a victory in the whole of Afghanistan."