Extremist political activists from Britain are provoking the migrant riots in Calais, the French authorities said today.

As police used tear gas and baton charges against hundreds of refugees trying to get to the UK for the third night in a row, the No Borders organisation was accused of inciting the violence.

It is a group made up of self-styled anarchists who campaign for all immigration controls to be scrapped.

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Amateur footage has emerged showing police with riot shields (left) advancing on a group of migrants (right) amid violent clashes in the last few days

It comes as amateur footage emerged showing police with riot shields advancing on a group of migrants amid violent clashes in the last few days.

French Interior Ministry spokesman Pierre-Henry Brandet said 'it is No Borders' who 'take advantage of the disarray of the migrants and push them into rioting.'

In numerous interviews with the media about the increasingly fraught situation in the French port town, Mr Brandet said 'everything was being done' to restore order.

Fabienne Buccio, the Pas de Calais prefect, also pointed to the 'increased aggression of the migrants' who were being 'organised by certain groups such as No Borders, who give them the tools to confront the forces of law and order.'

Mainly young men from the Jungle refugee camp on the edge of Calais have been seen brandishing iron bars and stones to throw at the police.

'They first of all try to stop the lorries around the camp so as to jump aboard,' said a local police spokesman.

There are currently some 6000 migrants sleeping rough in the Pas de Calais area. Police are pictured on patrol near the so-called 'Jungle' camp

'The aim is to try and stay in the vehicle until it passes through the Channel Tunnel or boards a ferry to England. When we try and stop what is going on, we are attacked.

'It is clear that those leading the fighting are not solely migrants. There are activists leading them on. They are unemployed activists from countries including Britain.'

No Borders was behind a riot at London St-Pancras station last month, as youths fought with the police during a protest against immigration controls..

It is clear that those leading the fighting are not solely migrants

Some of the activists live in caravans in the Jungle itself, advising those living there about how to get to Britain in the shortest possible time, and how to pass asylum exams.

'They deserve to get to the UK' is a typical statement on the No Borders website. It adds: 'No Borders is an anti-capitalist movement. Borders are created by, and serve, capitalist elites.

Many, though not all, people in the No Borders network also think of ourselves as anarchists.We believe a world without borders must also mean a world without states.'

Posters have also appeared in the camp urging migrants to defy British border police if they are stopped in the UK.

It reads: 'You do not have to answer any questions. You do not have to show them any documents.'