A British soldier was killed in in an explosion during a routine patrol in Sangin district of the southern Afghan province of Helmand, Britain's Ministry of Defence reported Thursday, according to DPA. The death, which occurred Wednesday night, brings to 137 the number of British soldiers killed in Afghanistan since the US-led invasion in 2001. 2008 was the year that saw the most casualties for Britain. That year saw 51 soldiers killed as opposed to 42 in 2007, and 39 in 2006. With around 8,000 soldiers, Britain has the second largest contingent in the 50,000 strong NATO-led International Security Assistance Force (ISAF).