A white substance found inside the White House late on Sunday, that promted a brief evacuation, tested positive for cocaine, sources told two news agencies on Tuesday.

Sources separately told the Associated Press and Reuters news agencies preliminary test showed the substance discovered in the West Wing was cocaine.

US Secret Service spokesperson Anthony Guglielmi did not confirm the finding but told the Washington Post the substance was undergoing further testing.

The West Wing contains the Oval Office, the cabinet room and press area, and offices and workspace for the president's staff.

Biden not at the White House

President Joe Biden and his family were at Camp David when secret service agents doing routine rounds found the white powder in an area accessible to tour groups.

"On Sunday evening, the White House complex went into a precautionary closure as officers from the Secret Service Uniformed Division investigated an unknown item found inside a work area," the Secret Service said in a statement.

"The item was sent for further evaluation and an investigation into the cause and manner of how it entered the White House is pending," the statement added.

Biden and his family returned to the White House on Tuesday.