The Group of 7, which includes Britain, France, Japan and others, announced the release of 100 million barrels over four months, effective immediately.
Yemen's capital, Sanaa, was bombarded overnight, after government forces reported some of the most intense clashes in years around Taiz, the country's third largest city.
The Coast Guard has intercepted two small boats it says was carrying illegal fuel to Cuba as the United States enforces an fuel blockade aimed at Cuba's Communist government.
Opposition groups are demanding the resignation of the election chief over the removal of 130 million voters from the rolls. The government denies influencing the exercise.
The State Department cited unspecified security concerns in announcing the unusual move. A closely fought presidential election in Brazil takes place on Sunday.