Six NATO soldiers were killed in three separate incidents Monday in southern Afghanistan, where the US-led alliance is mounting an ambitious campaign to flush out Taliban militants, the military said. Two NATO troops were killed in separate bomb explosions while three Australian commandos and a US soldier were killed when their helicopter crashed in the southern province of Kandahar, officials siad. The nationalities of the soldiers killed in the bomb attacks were not immediately released. NATO's deadliest days in Afghanistan Six NATO soldiers were killed in Afghanistan on Monday, the latest in a series of grim days that has made June one of the deadliest months for the alliance. Below is a chronology of some of the deadliest days of the war since the US-led ouster of the Taliban regime in 2001. According to an AFP tally, based on a count by the independent website, 281 foreign soldiers have been killed in Afghanistan this year. Last year was the deadliest yet, with 520 killed. --2005-- - June 28: 16 US military personnel, including eight Navy Seals, die when a Taliban rocket-propelled grenade hits their Chinook helicopter in Kunar province, east of Kabul. --2007-- - April 8: Six Canadian soldiers are killed when a bomb explodes near their vehicle in southern Afghanistan. - May 31: Seven soldiers, five of them Americans, are killed when a military transport helicopter crashes in Helmand province after a rocket attack. - July 4: Six Canadian soldiers and their Afghan interpreter are killed when a booby-trapped device hits their vehicle in the south. - November 10: Six NATO soldiers and two Afghan troops are killed in a Taliban ambush in northeast Afghanistan. --2008-- - July 13: Nine US soldiers are killed in clashes in Kunar province. - August 18: Ten French soldiers are killed in a Taliban ambush about 50 kilometres from Kabul. --2009-- - September 17: Six Italian soldiers are killed by a suicide bomb attack in Kabul. - October 3: Eight US soldiers and two Afghan soldiers are killed in fierce fighting against hundreds of militants in the eastern province of Nuristan, which borders Pakistani tribal areas that are havens for Al-Qaeda and Taliban sympathisers. - October 27: Eight US soldiers die in bomb attacks in the south. --2010-- - January 11: Three US, two French and one British soldier are killed in fighting in the south and east. - May 18: Eight NATO soldiers are killed, including six in a suicide attack on a NATO convoy in Kabul. - June 7: Seven US, two Australian and one French soldier are killed in bomb attacks in the south and the east. - June 8: Two more NATO soldiers are killed in southern Afghanistan. - June 21: Six NATO soldiers are killed, among them three Australians and an American in a helicopter crash in the south and an American and one other soldier in separate bomb explosions. In addition, on December 30, 2009, seven Americans working for the CIA and a member of the Jordanian intelligence services were killed in a suicide attack by a member of Al-Qaeda at a US base in the southeastern province of Khost near the border with Pakistan.