The US has announced another 30-day extension of a sanctions waiver allowing purchases of Russian seaborne oil to aid “energy-vulnerable” countries hit by the Iran war, reversing plans not to grant an extension.

Treasury secretary Scott Bessent said the Treasury was issuing the 30-day general license after a previous waiver lapsed on Saturday. This will allow temporary access to Russian oil and petroleum products stranded on tankers without violating severe US sanctions on Russian oil majors, he said.

“This general license will help stabilize the physical crude market and ensure oil reaches the most energy-vulnerable countries,” Bessent said.

Bessent, who last month told the Associated Press that no further extension of the Russian oil sanctions waiver was planned, on Monday argued that the measure would help reroute existing supply to countries most in need, allowing them to compete with China for previously sanctioned oil.

The action marks the second time the Treasury has allowed the sanctions waiver to lapse and subsequently extended it.

Two senior Democratic senators, Jeanne Shaheen of New Hampshire, and Elizabeth Warren of Massachusetts, blasted the move as an “indefensible gift” to Russian President Vladimir Putin.

“Every additional dollar the Kremlin earns from this license helps Putin finance his illegal war against Ukraine and kill innocent Ukrainians,” they said in a statement. They said the US sanctions relief was also not driving down gasoline prices at home or stabilising global energy markets.

The Trump administration last year slapped sanctions on Russian oil majors Rosneft and Lukoil to pressure Russia to end its war in Ukraine by depriving vital oil revenues to Moscow.

But after US-Israeli attacks on Iran drove up global oil prices, the Treasury first issued the temporary licence in March in an attempt to ease oil supply shortages and mitigate price spikes by releasing sanctioned Russian oil and petroleum products stranded in tankers. The waivers do not apply to oil now being pumped by Russia.

Analysts said the short-term waivers may help some individual countries dependent on Gulf oil supplies, but would do little to drive down US gasoline prices. “It is not yet clear whether these short-term authorizations have had any meaningful impact on U.S. gasoline prices,” said Stephanie Connor, a former policy director at the Treasury’s Office of Foreign Assets Control,adding that British and European sanctions on Russian oil purchases remain in place.

As in the previous waiver, the licence allowed purchases of Russian crude and petroleum products loaded on vessels as of 17 April, limiting the volume of the sales and not allowing access to Russian oil that had been more recently loaded.

Charles Lichfield, deputy director of the Atlantic Council’s GeoEconomics Center, said that the waivers would boost Russia’s oil revenues, already bolstered by higher oil prices, while offsetting the impact of increased Ukrainian strikes on Russian oil refineries and other infrastructure.

“Given the information coming out of the Russian economy that looks bad, this might be the time to really hit them with sanctions,” Lichfield said. “But I don’t see (that) the administration has come to that conclusion.”

On Monday, benchmark Brent oil futures prices rose about 2.6% to close above $112 per barrel due to growing concerns of tight supply.

Bessent, who is in Paris for a Group of Seven finance leaders meeting, said he wanted G7 and other allies to enforce Iran sanctions more strongly.