President Donald Trump threatened to send in federal authorities to Chicago if the city does not do more to cut its murder rate.

"If Chicago doesn't fix the horrible 'carnage' going on, 228 shootings in 2017 with 42 killings (up 24% from 2016), I will send in the Feds!" he tweeted.

Trump's claims apparently draw from a Chicago Tribune article which reported that there had been more shootings and homicides in the city so far this year than at the same time last year.

The figures and word "carnage" appeared on Fox News programme The O'Reilly Factor moments before the tweet.

A Chicago Police spokeswoman contradicted the figures in the article cited by Trump, and told NBC there had been 38 homicides, not 42, and 182 shootings, not 228, so far in 2017.

The spokeswoman said there had been the same number of shooting incidents and 33 homicides for the same period in 2016.

It was not immediately clear what form the federal intervention threatened by Trump might take.

Trump has previously called on Chicago mayor Rahm Emanuel to ask for federal assistance.

Mayor Emanuel has said the city would like increased government help in areas including gun control, gun tracking, prosecution for gun crimes and increased funding for more police officers. He also called for tougher sentences for repeat offenders.

Trump spoke strongly in favour of the Second Ammendment right to bear arms, and also defended controversial "stop and frisk" policies on the campaign trail.

Trump's message comes with murder rates in Chicago increasing in 2016, which was one of the bloodiest years in the city for decades. According to official figures, there were 762 murders in the city last year.

Trump's remarks followed protests in the city on Tuesday (24 January), with demonstrators gathering in downtown Evanston to oppose Trump's healthcare and environmental policies