WASHINGTON—The International Monetary Fund approved a $17 billion emergency rescue package to prevent a collapse of Ukraine's economy, marking a rare moment of consensus between Russia and Western nations battling over the former Soviet republic.

The signoff on Wednesday also unlocks an additional $15 billion in international financing, including loans and other funding from the U.S., Europe and the World Bank. It lets the new government in Kiev tap more than $3 billion of the IMF funds within days.

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