By Steve Holland and Daphne Psaledakis

WASHINGTON, April 15 (Reuters) – The ⁠United ⁠States on Wednesday threatened to ⁠sanction buyers of Iranian oil and said it believed China would pause ​such purchases as Washington enforces a maritime blockade on Iran. 

“We have told countries that if you are ‌buying Iranian oil, that if Iranian ‌money is sitting in your banks, we are now willing to apply secondary sanctions,” U.S. Treasury ⁠Secretary Scott ⁠Bessent told reporters at the White House. 

The U.S. maritime blockade on Iran ​began on Monday as the Iran war entered its seventh week. China previously bought more than 80% of Iran’s shipped oil.

“We believe (that with) this blockade … there will be a pause of Chinese buying,” Bessent said.

The U.S. ​Treasury has also written to two Chinese banks and “told them that if we can prove ⁠that ⁠there is Iranian money flowing ⁠through your ​accounts, then we are willing to put on secondary sanctions,” he added.

China’s embassy in the United ​States did not immediately respond ⁠to a request for comment on Bessent’s remarks.

The Trump administration has long said it is applying “maximum pressure” on Iran over its nuclear program and support for militants across the Middle East, though sanctioned oil has continued to reach China. 

The U.S. Treasury Department also targeted Iran’s oil transportation infrastructure, imposing ⁠sanctions on more than two dozen individuals, companies and vessels on Wednesday.

The move comes ⁠weeks after Washington issued a 30-day waiver of sanctions on Iranian oil at sea, which Bessent said last month allowed some 140 million barrels to reach global markets in a bid to relieve pressure on global energy supplies sparked by the war. 

Bessent confirmed on Wednesday that the waiver, issued on March 20 and set to expire April 19, would not be renewed, a move Reuters reported on Tuesday.

The U.S. has also not renewed the waiver on Russian oil at sea which expired on Saturday.

Reuters has also reported ⁠that the U.S. Treasury sent letters to China, Hong Kong, the UAE and Oman, identifying banks that have allowed Iranian illicit activity and warning that they face punitive U.S. measures. 

(Reporting by Steve Holland, Humeyra Pamuk, Christian Martinez, Ismail Shakil and David Ljunggren; Additional ​reporting by David Brunnstrom and Timothy Gardner; Writing by Daphne Psaledakis; Editing ​by Doina Chiacu, Michelle Nichols and Matthew Lewis)

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