London (CNN Business) US sanctions have forced a leading purchaser of Iranian crude exports to buy more oil from Saudi Arabia and the United States.

Sanjiv Singh, head of state-run refiner Indian Oil Corporation, told CNN Business that "whatever supplies were coming from Iran, they were well distributed amongst other countries."

Iran had been the third largest supplier of crude to India, which imports huge amounts of energy to fuel its growing economy. Iraq and Saudi Arabia were the only countries to export more to India.

But India was forced to turn to other sources after the Trump administration imposed sanctions on Iranian oil exports

India was one of only eight countries granted a waiver that allowed it to keep buying oil from Tehran, but that reprieve expired on May 2.