A small amount of white powder which authorities now believe is cocaine was found in the White House on Sunday, according to multiple media reports. The US Secret Service began an investigation after the substance was discovered Sunday evening. A source familiar told the newspaper that preliminary testing revealed the powder to be cocaine. Separately, The Daily Mail reported that the powder had been found in the library of the White House — an area frequented by many staffers as well as some tours. A source with knowledge of the situation characterised the area where it was found as a work area of the West Wing. Anthony Guglielmi, the Secret Service’s chief spokesman, told The Independent on Monday that agents were beginning “an investigation into the cause and manner” of how the powder entered the White House. He added that it was discovered during a routine sweep of the room. “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 DC Fire Department was called to evaluate and quickly determined the item to be non-hazardous. The item was sent for further evaluation and an investigation into the cause and manner of how it entered the White House is pending,” said Mr Guglielmi said. The president was not in the residence at the time of the investigation, according to the spokesman. Mr Biden spent the weekend at the Camp David residence, returning to Washington on Monday for an event with the National Education Association. Read More Watch live: Joe Biden addresses teachers and representatives of National Education Association Trump marks Independence Day by sharing vulgar attack on Biden and ominous 2024 warning Rudy Giuliani grilled by prosecutors about 'shouting match' in fight to overturn election