India is set to halt all crude imports from Iran because insurance companies in the country have said refineries processing the oil will no longer be covered due to Western sanctions, the head of refiner MRPL said on Friday.India is Iran's second-largest buyer, taking around a quarter of its oil exports worth around $1 billion a month."If cover is not available then all Indian refiners will have to halt imports from Iran or else they will have to take a huge risk," P.P. Upadhya, managing director of Mangalore Refinery and Petrochemicals Ltd, told Reuters in a telephone interview. MRPL is India's biggest buyer of Iran crude.