FRENCH border authorities blocked a much-anticipated aid convoy to the Calais refugee camp yesterday, leaving thousands of vital donations stranded on the other side of the Channel.

The 250-vehicle mission planned to arrive in France this Saturday, but the Calais prefecture branded the convoy a “risk to public order.”

Campaigners have called on Prime Minister David Cameron to intervene so that the hundreds of tons of clothes, food and fuel can be safely delivered to the 5,000 people living in the camp.

People’s Assembly secretary Sam Fairbairn, who helped organise the convoy, said: “This is Europe, there is supposed to be free movement of people.

“It’s unacceptable that we can’t even get across the Channel to deliver aid to desperate people.”

A letter signed by Calais Prefect Fabienne Buccio, arguing that “police forces cannot be mobilised in sufficient number” to secure people and goods reaching the port, was delivered to the convoy’s organisers yesterday, it listed football’s European Championship and France’s current state of emergency as obstacles to a safe passage.

The letter also highlighted that, given that previous refugee solidarity events have ended in confrontations between protesters and police, there were “serious reasons to believe that the demonstration of June 18 2016 could risk causing serious disturbance to public order.”

Convoy organisers said the group would still drive all the way to Dover and “demand that we are allowed to get on the ferry we have booked and paid for.”

A joint statement by the People’s Assembly, Stop the War and Stand Up to Racism said: “We are calling for a mass protest at this undemocratic and authoritarian decision.

“We demand that the British government tell the French authorities that this is unacceptable and that we should be allowed free passage.”

But a source told the Star that the French authorities were unlikely to budge and suggested that some campaigners might attempt to cross the border regardless.

The French embassy told the Star that it was for the Calais prefecture to comment on the matter, but the prefecture did not reply when contacted.

Seventy per cent of the British public believes the government should be “dong more to help those fleeing war and persecution,” according to a recent Amnesty International report.

In the months leading up to the convoy, the initiative received the endorsement of politicians and celebrities, including shadow chancellor John McDonnell MP and comedian Jo Brand.

It was also supported by several trade unions, including Unite, Unison and PCS, and charities such as the Muslim Association of Britain, Humanitas and the Woodcraft Folk.