"US claims it favors diplomacy; not Trump's failed policy of 'maximum pressure'," Iran's Foreign Minister Mohammad Javad Zarif wrote on Twitter.

"Yet (US Secretary of State Antony Blinken) boasts abt blocking Korea from transferring our OWN money to the Swiss Channel -- only used for food & meds," he added.

"Repeating the same policy won't yield new results."

Zarif's comments came hours after Blinken signaled US opposition to the release of billions of dollars in Iranian funds from South Korea unless the Islamic republic returns to full compliance with the nuclear accord.

South Korea had said last month it agreed on a way forward to release billion of dollars frozen from Iran's oil sales but was awaiting Washington's approval, AFP reported.

US President Joe Biden, who defeated Trump at the ballot box in November, has signaled his readiness to revive the deal that has been largely left in tatters by his predecessor's decision to withdraw from it in 2018.

But Biden insists Iran first return to its nuclear commitments, most of which it suspended in response to US sanctions, while Tehran demands Washington take the first step by scrapping them.

Iran was a key oil supplier to resource-poor South Korea until Washington's rules blocked the purchases.

According to government spokesman Ali Rabiei, Iran has $7 billion of funds blocked in Seoul.

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