WASHINGTON — The White House says eight more countries have signed a statement blaming Syrian President Bashar Assad for a chemical weapons attack and calling for a strong international response.

The additions announced Tuesday bring the total number of supportive countries to 33, up from 25 on Monday.

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The statement was released last week at the close of an economic summit in Russia. It had 11 original signers, including the United States. The latest countries to sign are Georgia, Guatemala, Kuwait, Malta, Montenegro, Panama, Poland and Portugal.

The statement doesn’t explicitly call for military action against Syria, which President Barack Obama has been lobbying for. But administration officials say the statement is an implicit endorsement because the U.S. is publicly discussing potential military strikes.