The Port of Calais has now re-opened after being forced to close when migrants broke into the harbour and occupied a ferry.

It is believed around 50 refugees got on-board the P&O vessel the Spirit of Britain in an attempt to reach the UK. Reports from Calais say French police managed to get the group to disembark.

This action came after hundreds of migrants stormed the site after a day of tensions.

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The Port of Dover said on Saturday night, just before 9pm the situation had been resolved and the docks had re-opened.

Its statement added: "Following a period of migrant activity at the Port of Calais which caused disruption to ferry sailings earlier this evening, services are returning to normal.

"The Port of Dover remained open for business throughout the period of disruption."

"Traffic is free flowing along the M20/A20 and M2/A2 approaches to Dover and there is space available on sailings with both operators."

The statement added the situation would continue to be closely monitored.

Trouble flared earlier today when a protest to support those living in squalid conditions near Calais had drawn around 2,000 people to the northern French town. The demonstration called for borders with the UK to be opened up for refugees.

Labour leader Jeremy Corbyn also visited Dunkirk on Saturday where about 4,000 migrants are living.

A group called Calais Solidarity said on Twitter around 500 people breached the fences at the French docks, 100 made it further into the harbour and around 50 climbed on board the ferry.

It claims officials went on top of the ferry using high pressure jets of water from hoses to try and get the refugees to move.

It reported customs drivers and security as being 'dumbfounded' at what was happening.

Earlier this evening P&O Ferries warned people to expect delays of around an hour-and-a-half to two hours on its services.

It described the situation at Calais as a 'security incident.'

But at 8pm it said vessels were being allowed to dock and loading should be able to start.

Earlier the ferry company had said: "Our vessels are delayed until such time as given the all clear to load."

Earlier this evening the Port of Dover said it had no idea how long delays would be. They affected P&O services, but DFDS ferries which also use Dover sail into Dunkirk and were not affected by the closure.

The Port of Dover remained open for business and customers are still advised to contact their chosen ferry operator before travelling.

Travellers will now have to contend with a Eurotunnel closure which comes into force after 9pm tonight.

The tunnel is shutting so an overnight safety exercise can take place and all services will be suspended.

In UK the last departure will be 9.20pm, and in France it will be 10.20pm.

The first departure leaving the UK will be 6.20am and from France, 7.20am.

Advice to customers is to arrive 45 minutes beforehand for check-in and the company apologised for any inconvenience.

The situation in Calais is part of a wider migration crisis caused by people fleeing war in countries such as Syria.