A spokesman at the U.S. Embassy in Madrid says it has called in Spanish police to inspect a suspicious letter.

Spokesman William Ostick says the letter has been isolated but that it could be some time before the contents of the envelope are determined.

He says the entrance to the embassy was sealed off temporarily after the letter arrived shortly after midday Wednesday.

Ostick says the letter resembled others sent to at least eight U.S. embassies on Tuesday, several of which turned out to contain flour.

A police spokesman said they had sent in explosive and chemical experts to check the envelope.