A white substance that sparked an emergency evacuation at the White House on Sunday night tested positive for cocaine.

The substance was found in a work area at the secure building during a routine inspection, the US Secret Service said.

The preliminary positive test was first reported by the Washington Post, citing fire and law enforcement sources.

President Joe Biden and his family were away at the Camp David residence when the substance was found.

The White House complex was closed as a precaution around 20:45 local time (01:45 BST) on Sunday after Secret Service officers found the white powder "inside a work area" of the West Wing, Secret Service spokesperson Anthony Guglielmi told the BBC in a statement.

Mr Guglielmi said the fire department was quickly called and found the substance to be "non-hazardous".

He did not confirm the preliminary test results, saying the item has been sent for additional testing and that an investigation is ongoing, including on how the substance entered the White House.

The BBC's US partner, CBS News, reported a senior law enforcement source as saying the substance was found in a storage facility in a cupboard routinely used by White House staff and guests to store mobile phones.

CBS reported that two law enforcement officials and a recording of a radio dispatch from Sunday confirmed the substance tested positive for cocaine soon after it was found.

Cocaine is a Schedule II drug under the Controlled Substances Act, meaning it has a high potential for abuse, according to the US Drug Enforcement Administration.

The West Wing is a large, multi-level part of the White House that contains the offices of the president of the United States, including the Oval Office and the Situation Room.

It also houses the offices of the vice-president, the White House chief of staff, the press secretary, and hundreds of other staff who have access.