PARIS—U.S. allies are planning to release close to 60 million additional barrels of oil from their reserves, officials familiar with the matter said, joining the Biden administration in an effort to tame prices after they rose sharply when Russia invaded Ukraine.

The 31-member nations of the International Energy Agency—which include the U.S., most of Europe, Australia, Japan, Mexico and others—are planning to announce a new reserve release totaling 120 million barrels, officials said, the largest release in the IEA’s 47-year history. Around half of that amount will come from U.S. reserves, which were included in Washington’s previously announced decision to release 180 million barrels of oil over six months.

That leaves around 60 million barrels of additional oil that will hit the market because of the IEA decision, which is expected to be announced by the end of the week. Those barrels are expected to be released over six months to track the U.S. schedule, an official said. IEA nations on March 1 announced the release of 60 million barrels—including 30 million barrels from the U.S.—in what was then the agency’s biggest-ever release of reserves.

Futures for Brent crude, the global benchmark, traded down 5.2% to $101.07 a barrel on Wednesday. The IEA said last week that its members would release additional reserves but didn’t say how much.

Western officials hope the new supplies will cushion their economies as many buyers move to stop purchasing oil from Russia, the world’s second largest crude-oil exporter and third largest producer. The U.S. has already imposed sanctions on Russian oil imports, while European nations are debating whether to do so as well. Europe relies on Moscow for around a quarter of its oil imports.

Analysts are skeptical whether reserve releases will lower prices for long. Placing stored oil on the market can sometimes boost prices later on when nations buy crude to replenish their stocks, they said.

Western officials say the move can buy their economies time to replace Russian oil with supplies from other regions, mainly the U.S. and the Middle East. The Biden administration is counting on U.S. oil producers to boost production toward the end of the year to fill the supply gap.

But the countries of the Organization of the Petroleum Exporting Countries, or OPEC, have resisted repeated entreaties from Western governments to boost production since the Russian invasion. They, along with Russia and its allies, a group called OPEC+, have stuck to a previously agreed plan backed by Moscow that calls for a relatively modest increase in output.

India, meanwhile, has been stepping in to buy steeply discounted Russian oil that is no longer able to find a home in the U.S. or some European countries.

Write to Matthew Dalton at Matthew.Dalton@wsj.com