Inauguration: Four more journalists could face up to 10 years in prison after covering anti-Donald Trump protests

A further four journalists are facing up to 10 years in prison and £20,000 fines after they were arrested while covering unrest in Washington DC after Donald Trump’s inauguration.

They have been named as Jack Keller, a producer for a web documentary series, Matt Hoppard, an independent journalist who was live-streaming the events online, Shay Horse, an independent photojournalist and activist, and Aaron Cantu, whose LinkedIn profile describes him as an editorial and web intern at The Nation magazine.

They were arrested at the same time as Evan Engel of the technology news website Vocativ and Alex Rubenstein of Russia Today (RT) America.

All six were covering a protest march which became violent when a group of masked protesters clashed with police and smashed windows of local businesses.

The criminal complaint said they had been charged with a rioting offence under section 1332(b) of Washington DC's criminal code which carries a maximum penalty of up to 180 days in prison and a fine of up to $1,000 (£800), according to the Committee to Protect Journalists (CPJ).

But the language of the complaint refers to rioting that results in bodily harm or more than $5,000 (£4,000) in damage – a much more serious offence that carries a maximum penalty of a $25,000 (£20,000) fine and 10 years in prison.

All six appeared in the US capital's Superior Court and were released on bail until further hearings in February and March.

Press freedom groups have expressed outrage at their detention and called for the charges to be dropped immediately.

Calling the charges “clearly inappropriate”, Carlos Lauría, a programme coordinator at the CPJ, said they sent a “chilling message” to journalists covering future protests.

A spokeswoman for Vocativ denounced the arrest of Mr Engel and the other journalists, saying it was an “affront to the First Amendment and journalistic freedom”.

She said the police had seized Mr Engel’s camera and mobile phone and insisted the website would “vigorously contest this unfounded and outrageous charge”.

News of the arrests comes as Mr Trump’s press secretary, Sean Spicer, became embroiled in a row with the US media over the new President’s claim that outlets like CNN were lying about the size of the inauguration crowd.

Several media outlets tweeted overhead pictures comparing the crowds at Mr Trump’s swearing-in ceremony with that of Barack Obama in 2009 and 2013. It showed the crowd had thinned out as it spread along Washington DC's National Mall.

Mr Spicer issued a furious denunciation of the press for reporting the difference in numbers, and claimed Trump had had the largest turnout for an inauguration ever, before threatening to hold the media “accountable” for its “lies”.

He was later defended by the senior counsellor to the President, Kellyanne Conway, who claimed he was presenting “alternative facts” during an interview with CNN when the host accused Mr Spicer of lying.