According to the State Department, the sanctions are part of Washington’s ongoing “maximum pressure campaign” aimed at disrupting Tehran’s energy export system and curbing its alleged financial support to terrorist organizations.
U.S. Treasury Secretary Scott Bessent, emerging from the talks, told reporters that when it comes to Russian oil purchases, the "Chinese take their sovereignty very seriously.”
Former US President Trump abandoned the 2015 Iran nuclear deal and reimposed sanctions on Tehran in late 2018.
The world's fifth-largest crude importer won a six-month waiver in November from U.S. sanctions on Tehran's oil exports, but did not immediately start imports, mainly due to payment and insurance issues.
The company has a deal to buy 180,000 barrels per day (bpd)Iranian oil this fiscal year.
"Insurance companies are providing for asset cover but are not covering the crude kept in storage," the official said on condition of anonymity.
Iran is regaining market share at a faster pace than analysts had projected since sanctions were lifted in January, and Iran's senior government official said it sees its oil production at 4 million barrels per day by year-end.
A source at state-owned National Iranian Oil Co (NIOC) told Reuters that Iran will charge in euros for its recently signed oil contracts with firms including French oil and gas major Total, Spanish refiner Cepsa and Litasco, the trading arm of Russia's Lukoil.
This unfortunate group sells some physical crude cargoes at prices that are closer to USD 10 a barrel, thanks to an abundance of the "sour" grades they produce and a consumer base that favors higher-quality "light" oils from other origins.
Oil prices had briefly stabilized in the previous session, but only after hitting the lowest since 2003 as western sanctions against Iran were lifted, allowing the country with the world's fourth-largest oil and gas reserves to return in full to the market.
This means that the OPEC member will now be able to export oil, sending a wave of fear across the already weak markets which have been plagued by an energy supply surplus.
On Saturday, the UN nuclear watchdog said Tehran had met its commitments to curtail its nuclear program, and the United States immediately revoked sanctions that had slashed the OPEC member's oil exports by around 2 million barrels per day (bpd) since their pre-sanctions 2011 peak to little more than 1 million bpd.
US crude futures were down by more than 4.5 percent at USD 29.67 per barrel at 1219 GMT, after posting their first significant gains for 2016 in the previous session. The contract hit USD 29.39, their lowest since November 2003
Brent and US crude oil were on track to close lower for a third consecutive week, down roughly 20 percent from their 2016 highs.
West Texas Intermediate (WTI) was down 33 cents at USD 30.87 a barrel at 0103 GMT (2003 EDT). On Thursday the contract rose 72 cents, or 2.4 percent, to settle at USD 31.20. It hit a 12-year low of USD 29.93 earlier this week.
Brent dropped as far as USD 29.73, the lowest since February 2004 and down more than 1.5 percent. It was down 47 cents at USD 29.84 a barrel at 0145 GMT and the contract has fallen every trading this year.
US West Texas Intermediate crude (WTI) was up 44 cents at USD 30.88 a barrel at 0144 GMT. On Tuesday, it fell 97 cents to close at USD 30.44 a barrel, after touching a low of USD 29.93, which was last seen in December 2003.
US crude tumbled below USD 31 a barrel today, extending a sell-off that has sent the commodity to more than 12-year lows, hit by a global supply glut, a strong dollar and tepid demand.
US crude West Texas Intermediate (WTI) CLc1 were trading at USD 31.34 per barrel at 0805 GMT on Tuesday, down 7 cents from their last settlement and almost 19 percent lower than at the beginning of the year. WTI has shed over 70 percent in value since the downturn began in mid-2014.
US crude West Texas Intermediate (WTI) CLc1 dropped more than 2 percent in early Monday trading to a low of 32.43 per barrel before edging back to USD 32.51 by 0038 GMT (07:38 p.m. EST), still down 65 cents
The equity and currency turmoil in China that rippled through world markets during Russians' 10-day festive holiday pushed Brent crude futures to around USD 32 a barrel, down from USD 45 at the start of December and a step closer to the USD 20 price trough predicted by Goldman Sachs.
Futures of global oil benchmark Brent and US West Texas Intermediate (WTI) crude seesawed through the day, settling slightly lower after stock prices on Wall Street gave up their earlier strength. The two benchmarks hit 12-year lows earlier in the week after China's stock market crash roiled global markets.
Fast-forward five months and in some parts of the world the forecast has already proved correct. Canadian physical crude has been selling this week at below USD 20 per barrel, less than it costs to extract and transport. Traders in the options market, meanwhile, are taking protection against prices falling below USD 25.
US crude West Texas Intermediate (WTI) was trading 63 cents higher at USD 33.90 a barrel after settling at USD 33.27 on Thursday. In the last session, it hit its lowest since late 2003 at USD 32.10.
A huge supply overhang and near-record output levels also continued to drag on oil prices, which have now shed 70 percent in value since the current downturn began in June 2014, causing pain to companies and governments that rely heavily on oil revenues.