Donald Trump has retweeted the British far-right commentator Katie Hopkins and launched another attack on Sadiq Khan.

Referring to a message from Hopkins that the Met’s Twitter account had been targeted by hackers on Friday night, in which she said officers had “lost control of London streets” and “lost control of their Twitter account too”, Trump tweeted: “With the incompetent mayor of London, you will never have safe streets!”

It is Trump’s latest move in an ongoing spat with Khan, during which he called the London mayor a “national disgrace” and “stone cold loser”, comments dismissed by the London mayor as childish.

Minutes before his latest jibe against Khan, Trump retweeted videos posted by Hopkins that supported the US president’s recent racist attacks on four US congresswomen.

Trump shared two messages from Hopkins praising his leadership and criticising Alexandria Ocasio-Cortez and her fellow Democrats widely known as “the Squad”.

Hopkins tweeted: “How I wish we had such leadership in the UK. Don’t like this country? Don’t like what it gives you? Then leave.”

Hopkins, who once wrote a column comparing migrants to “cockroaches” and “feral humans”, was last week banned from speaking at Eastbourne’s new conference centre.

Earlier this month Trump retweeted a tweet from Hopkins in which she praised a number of far-right politicians and said “the fightback by proud nations is on”.