The annual value of official global trade in small arms and light weapons has increased to 8.5 billion dollars a year, due mainly to purchases by the US government for the wars in Iraq and Afghanistan, a Swiss survey said Monday. The Small Arms Survey 2012 said the new official estimate more than doubled the value of small arms transfers since the last survey in 2006. The UN launched the survey at its headquarters in New York as it began a two-week review of a programme of action to prevent and combat the illicit trade in small arms, parts and ammunitions. The Graduate Institute of International and Development Studies in Geneva said it had been able to compile data for the survey because of strong transparency policies in some of the arms exporting countries. The top exporters and importers include the United States, Italy, Germany, Brazil, Austria, Russia, China, France, South Korea, Belgium and Spain.