Pentagon says plan for Poles to give Soviet-era jets to US ‘not tenable’ as Ukraine cities await promised Russian ceasefire

• Russia-Ukraine war: latest updates

The Pentagon has dismissed Poland’s plan to hand the US its MiG-29 fighter jets to boost Ukraine’s fight against Russia, as Moscow officials said they were ready to provide humanitarian corridors on Wednesday morning for people fleeing Kyiv and four other cities.

Washington appeared surprised by the announcement by Polish foreign minister, Zbigniew Rau, who said on Tuesday that his government was “ready to deploy – immediately and free of charge – all their MiG-29 jets to the Ramstein airbase and place them at the disposal of the government of the United States of America.”

Saudi Arabia and the United Arab Emirates reportedly declined to arrange calls with Joe Biden in recent weeks as the US seeks to increase oil supply after formally banning Russian oil imports on Tuesday, pushing oil prices to $130 a barrel, the highest level in 14 years.

Venezuela released at least two jailed US citizens on Tuesday, according to multiple sources, in an apparent goodwill gesture. It follows a visit to Caracas by a high-level US delegation that focused not only on the fate of Americans held in Venezuela, but on the possibility of easing US oil sanctions on the Opec member, which is a close Russian ally.

The Chernobyl nuclear power plant is no longer transmitting data to the UN’s atomic watchdog, the agency said, as it voiced “deep concern” for staff working under Russian guard at the captured Ukrainian facility. International Atomic Energy Agency chief Rafael Grossi voiced fears for nuclear safety and offered to travel to the site.

Foreign volunteers will qualify for Ukrainian citizenship, first deputy interior minister Yevhen Yenin said in a TV interview. Nearly 20,000 people from 52 countries have signed up to become volunteers in the war with Russia.

More western brands continued to suspend operations in Russia, with Starbucks, Coca-Cola and Pepsi joining McDonald’s in halting sales.

Nato’s secretary general, Jens Stoltenberg, warned Russia that any attack on supply lines in Nato countries carrying arms and ammunition to Ukraine would be grounds for retaliation. “An attack on Nato territory, on Nato forces, Nato capabilities, that would be an attack on Nato,” Stoltenberg said.

British foreign secretary Liz Truss will meet her US counterpart Antony Blinken in Washington on Wednesday to discuss what more can be done to help Ukraine and reduce energy dependency on Russia. Truss called the invasion of Ukraine “a wake-up call for free democracies”.