WASHINGTON — President Trump on Saturday resumed his 3,675-mile feud with the mayor of London, calling him “a disaster” who should be turned out of office after a spate of stabbings in Britain’s capital.

“LONDON needs a new mayor ASAP,” Mr. Trump wrote on Twitter, referring to Sadiq Khan, the mayor he has been fighting with from a distance for three years. “Khan is a disaster - will only get worse!”

The president offered his harsh view while reposting a tweet on crime over the past day written by Katie Hopkins, a conservative commentator who referred to “20 hours in Stab-City,” in which four stabbings and a shooting resulted in three deaths. “This is Khan’s Londonistan,” Ms. Hopkins added, using a disparaging term referring to the city’s Muslim population. Mr. Khan is Britain’s first Muslim mayor.

The president weighed in while visiting his golf club in Virginia. Five hours later, after returning to the White House, Mr. Trump posted a follow-up attack on Mr. Khan. “He is a national disgrace who is destroying the City of London!” the president wrote.