Trump uses Scotland Yard IT service hack to attack London Mayor

US President Donald Trump on Saturday used a brief hack into Scotland Yard's news and Twitter service to reopen his feud with London Mayor Sadiq Khan, blaming him for the breach.

A series of bizarre messages from the official news website and Twitter were sent out to more than a million followers of the Metropolitan Police accounts overnight on Friday.

"With the incompetent Mayor of London, you will never have safe streets," Trump said, alongside a retweet of a Twitter message related to the hack.

The US president and Khan have repeatedly clashed in the past, exchanging Twitter barbs against each other.

The Met Police clarified in a statement that there had been no hack of the Met Police's own IT infrastructure but that the breach was linked with a third-party news service it uses.

We are assessing to establish what criminal offences have been committed, the force said in a statement.

It adds: The Met Police Press Bureau uses an online provider called MyNewsDesk to issue news releases