MISSOULA, MONTANA (BLOOMBERG) - President Donald Trump has praised a Republican congressman for assaulting a reporter who asked him a question on the eve of a special election last year.

Mr Trump celebrated the episode as he introduced Montana Representative Greg Gianforte at a rally in Missoula, Montana, on Thursday evening (Oct 18).

Mr Gianforte pleaded guilty to assault after he body-slammed Guardian reporter Ben Jacobs for asking a question on healthcare legislation.

The next day, Mr Gianforte won a special election for Montana's US House seat.

"Any guy that can do a body-slam, he's my kind of guy," Mr Trump said, mimicking the action to the cheers of the crowd. "I shouldn't say that, but there's nothing to be embarrassed about."

He called Mr Gianforte "a great guy, tough cookie".

Mr Trump raised the incident amid calls for a stronger response from his administration to reports that US-based journalist Jamal Khashoggi was ambushed inside the Saudi Arabia's consulate in Istanbul, then tortured, killed and dismembered.

While members of Congress are threatening to sanction the Saudi government, Mr Trump, who has cultivated closer ties to the kingdom, has taken a cautious stance, stressing the long alliance between the US and Saudi Arabia.

But as he left Washington to travel to the rally on Thursday, Mr Trump warned of "very severe" consequences for the apparent killing.

After his election in May 2017, Mr Gianforte was sentenced to serve 40 hours of community service and attend 20 hours of anger management classes for throwing the reporter to the ground and breaking his glasses.

He also wrote a letter of apology in which he acknowledged assaulting Mr Jacobs for asking "a legitimate question about healthcare policy".