China, India, Japan and South Korea have worked their way around an EU insurance ban that took effect July 1
Iran's top crude oil buyers - China, India, Japan and South Korea - have worked their way around a European Union insurance ban that took effect July 1.
Insurance companies based in the EU are not allowed to provide cover for ships that carry Iranian cargo.
The EU sanctions are aimed at the protection and indemnity (P&I) clubs based in the EU, which dominate the marine insurance industry. They follow a series of other sanctions that the US has put in place against Iran, including one against oil-related transactions that took effect on June 28.
Washington and its allies hope that the measures force Teheran to halt its nuclear programme, which they believe is being used to develop weapons, a claim Iran denies.
Following are details on how Iran's four biggest oil customers - who together, purchase more than half of Iran's oil exports - are dealing with the sanctions.