Norwich South MP Clive Lewis says a potential £5,000 fine for setting off a smoke bomb would be 'money well spent' if it meant preserving free speech.

The Labour frontbencher and his colleague MP Lloyd Russell-Moyle were photographed holding smoke bombs during an anti-Brexit demonstration in London on Tuesday.

They were part of a group of Labour MPs who gathered on Westminster Bridge to unfurl a 32ft-long banner that read 'Love Socialism, Hate Brexit'.

But the two MPs could now face a fine of up to £5,000 as it is an offence to throw or discharge smoke bombs, which are classed as fireworks.

Shadow treasury minister Mr Lewis said while he was unaware setting off a smoke bomb was an offence, he had no intention of using his 'ignorance of the law' as a defence.

He said: 'So far I've not been contacted by any authority.

'However, if £5,000 is the cost of MPs preserving free speech, raising awareness, and allowing me to tell my grandchildren I fought to stop a damaging and destructive Tory Brexit, it would be money well spent.'

The use of flares by the protest group so close to the Houses of Parliament led to police arriving by boat to inquire what was going on.

The MPs earlier congregated outside Portcullis House, where many MPs have offices.

In a Twitter post on Tuesday, Mr Lewis said he was proud to stand with colleagues for the 'Love Socialism, Hate Brexit' banner drop in Westminster.

He said: 'We stand in support of Jeremy Corbyn in our campaign against #Brexit and our fight for a better society for the many.'

In response to a national newspaper publishing a story about the smoke bomb, Mr Lewis said: 'Yes I was 'smoking' but I didn't inhale'.'

Speaking about the protest, Marsha de Cordova, Labour MP for Battersea, said: 'We're sending a clear message of solidarity to the leadership that we believe the British people have been let down.

'When it comes to Brexit we need to give the people the final say.'

Photographs from the event show Mr Lewis and Mr Russell-Moyle either side of the group letting off red smoke over the River Thames.

A total of 13 Labour MPs gathered to take part in the demonstration.