U.S. President Joe Biden has said he was surprised that classified documents were discovered in an office he used before he was elected.

Biden said he doesn’t know what’s in the documents, but that he believed they were handled properly by his lawyers. "We’re cooperating fully,” he said Tuesday at a news conference in Mexico City with Mexican President Andres Manuel Lopez Obrador and Canadian Prime Minister Justin Trudeau.

"People know I take classified documents, classified information seriously,” he said. "I was briefed about this discovery, and surprised to learn that there are any government records that were taken there to that office.”