LONDON, Aug 12 (Reuters) - Britain will deploy hundreds of military personnel to Afghanistan to help British nationals and local translators get out of the country, defence secretary Ben Wallace said on Thursday as the security situation there worsens. The British embassy in Kabul will be moved to a more secure location and will remain manned by only a core staff. The deployment of protection forces and logistical support has been triggered by rising violence as Taliban fighters capture cities across Afghanistan after U.S. and allied troops withdrew. "I have authorised the deployment of additional military personnel to support the diplomatic presence in Kabul, assist British nationals to leave the country and support the relocation of former Afghan staff who risked their lives serving alongside us," Wallace said in a statement. "It is a long planned process and it was important with the current situation on the ground in Afghanistan to make the decision to move to that phase," he told a separate briefing. The British ambassador Laurie Bristow will be among those staying in Kabul. Last week Britain advised all its nationals in Afghanistan to leave. The first troops are expected to arrive by the end of the week, and the number could eventually rise to 600. They will include medics and specialist planners to help manage the withdrawal. The several thousand being helped out of the country include Afghan interpreters and other local personnel eligible for relocation to Britain as well as others who hold British passports. They will take commercial flights. 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. The speed and violence of the Taliban advance has caused recriminations among many Afghans over U.S. President Joe Biden"s decision to withdraw U.S. troops and leave the Afghan government to fight alone. Britain also withdrew its troops as part of a coordinated move between NATO and the United States.