Iran is keeping up oil sales through "unconventional" means to circumvent US sanctions, Oil Minister Bijan Namdar Zanganeh said in an interview published Saturday.
"We have unofficial or unconventional sales, all of which are secret, because if they are made known America would immediately stop them," he said, quoted by the oil ministry's SHANA news agency.
Zanganeh declined to give details on Iran's oil exports, saying he would not disclose figures until sanctions were lifted.
In May 2018, Washington withdrew from Iran's 2015 nuclear deal with world powers that granted Tehran sanctions relief in exchange for curbs on its atomic program.
Washington reimposed oil sanctions on Iran last November, but initially gave eight countries, including several allies such as China, six-month waivers.
Iran's oil shipments tumbled to 750,000 barrels per day in April compared to 1.5 million in October, according to data compiled by Bloomberg.
The White House in May ended all the waivers as part of a "maximum pressure" campaign against Tehran.
According to Zanganeh, the US has reached an "evil maturity" in tightening the noose on Iran's economy using "smart sanctions".
"The most severe organized sanctions in history are currently being imposed on Iran," he said.