The campaign wants the abolition of all borders and free movement for all
Activists campaigning for the abolition of migration controls are holding a demonstration march in Calais.
The organisers, mainly from the UK, France and Belgium, are holding a week-long protest camp in Calais and hope up to 2,000 people will march.
The No Border Camp told the BBC about 500 people were staying there so far, including campaigners, migrant support groups and migrants living in the area.
Police have arrested some activists in the town but have not entered the camp.
Alex Clarke, 30, from London, said a group of several hundred people had walked from the camp and were gathering in Calais before setting off on a demonstration march through the town.
She told the BBC there was a heavy police presence but "for now it's a really good atmosphere".
She added: "We're just hoping for a safe demonstration really. There's been a lot of hyped-up stories about us trying to rip down the border.
"A broad section of people are here and what they are calling for is a freedom of movement, but that doesn't equate to tearing down the border."
Protesters had complained of heavy-handed policing which they said had gradually increased since the camp event began on 23 June.
They said there were helicopters circling overhead, and some 1,500 armed officers were patrolling the town and the area around the authorised camp - in a park outside Calais - and manning several checkpoints.
Charities distribute food and clothing to people in the 'jungle'
A Calais police official told the BBC a helicopter was flying over the camp. He said he "couldn't say" how many officers had been deployed but confirmed they were carrying shields, batons and guns, plus tear gas.
The campaign group said the camp was non-violent and have vehemently denied some press reports suggesting they intended to storm the Channel Tunnel on Saturday to help migrants waiting to reach Britain enter the country.
'Freedom of movement'
The No Border Camp - one of several to have been organised around the world - was aiming to highlight the plight of migrants living in "refugee camp" conditions in Calais, said campaigner Sam Davies.
Organised by a broad coalition - including the UK No Borders network - it also calls for the freedom of movement for all, with the abolition of borders and all immigration controls.
There are estimated to be about 1,000 migrants in makeshift camps, known as "the jungle", in Calais.
Most - from countries such as Afghanistan, Somalia and Eritrea - are hoping to enter Britain, sometimes by smuggling themselves into lorries.
The camps began to appear after France closed the Sangatte Red Cross refugee centre in 2002.