A white powder that was found in the White House and sparked a brief security alert has been confirmed to be cocaine, the Secret Service said Wednesday.

The powder's discovery in the West Wing on Sunday was initially treated as a potential danger, prompting a brief evacuation.

An initial test of the substance performed by the Washington, DC, fire department then said it appeared to be cocaine -- not some sort of threat or attack.

This prompted a flurry of speculation in US media over who could have left the drug. President Joe Biden and his family were away from the White House all weekend.

Anthony Guglielmi, spokesman for the US Secret Service, which protects the White House, said it was "just confirmed that substance found was cocaine and our investigation is ongoing."

According to US media reports, the cocaine was found on the ground floor of the West Wing, which includes the Oval Office and other crucial facilities.

It was reportedly found in an area where visitors taking part in White House tours are told to leave their cell phones for security purposes.