Migrants in Calais have been given four days to pack up and leave as French authorities push ahead with the demolition of the notorious 'jungle' camp.

Under a new expulsion order, hundreds of refugees have been told to remove their makeshift homes and possessions by 8pm local time on Tuesday.

Those who refuse to leave will be forcibly removed by police.

The order has been issued by the state authority in Calais and affects between 800 and 1,000 migrants who live in the southern sector of the camp.

Migrants have built up a makeshift community there, with shops, cafes, churches and mosques. All will be razed.

The migrants, many of whom are Syrians or Iraqi refugees, have been told to move to nearby containers or welcome centres around France.

But eight associations working in the camp, including Doctors of the World, have warned that the alternatives are not suitable.

They are "very far from answering the needs of the problems encountered,” the associations wrote in a protest letter to the French interior minister.

In total the ‘jungle’ is home to some 4,000 migrants, many of whom hope, ultimately, to cross the Channel to Britain.

Conditions in the camp have been described as horrific.

On Thursday 145 actors, sports personalities and celebrities, including Jude Law, Sir Richard Branson and Gary Lineker, signed an open letter to the Prime Minister to allow children stuck in the camp to enter the UK.

"These are innocent, vulnerable children caught up in red tape with the frightening prospect of the demolition of the Jungle hanging over them," said Law, who organised the letter.

"David Cameron and the British government must urgently work with the French authorities to alleviate this humanitarian crisis."