LONDON (Reuters) - Four British soldiers have been killed in a single day while on patrol in southern Afghanistan, the Ministry of Defence said on Friday. It was the armed forces worst loss of life in one day since June 2008. The four died in three separate incidents on Thursday in Helmand, one of the most violent areas in the country and heartland of the Taliban movement. One of the deaths had already been announced on Thursday. The latest deaths bring the number of British soldiers to have been killed in action in the country this year to 20. The MoD said two soldiers, one from the 1st Battalion The Royal Gurkha Rifles and the other from 173 Provost Company, 3rd Regiment, died in a suicide attack in Gereshk. The NATO-led force in Afghanistan said that 16 Afghan civilians died in the same attack and 30 Afghan civilians were wounded. With heavy heart we report another extremely sad situation, where lives of our courageous soldiers have been sacrificed for the greater good of the Afghan people, said spokesman for Task Force Helmand, Lieutenant Colonel Nick Richardson. Earlier the MoD said a soldier with The Rifles 2nd Battalion had died in an explosion while travelling in a Jackal patrol vehicle near Sangin in Helmand. In a third incident on Thursday, a soldier from the Black Watch, 3rd Battalion the Royal Regiment of Scotland, died from a gunshot wound suffered during a patrol with the Afghan National Army near Musa Qala in Helmand. The deaths bring the number of British soldiers killed in Afghanistan since the start of operations in October 2001 to 157, the MoD said.