71% rise in illegal immigrants trying to reach Britain via NI
The number of illegal immigrants trying to enter the UK through Northern Ireland has risen significantly over the past three years.
Home Office figures show that 468 people were intercepted in 2014/15, including those who crossed the border with the Republic.
This is up 71% up on the 274 total in 2012/13, although the numbers are miniscule compared to the crisis in Calais and the Mediterranean.
The figures were revealed as David Cameron admitted that the impact of chaos in Calais is set to last all summer.
Attempting to take charge of the response after returning from his visit to south east Asia, the Prime Minister called the situation "unacceptable" and declared: "We are absolutely on it. We know it needs more work."
The Prime Minister pledged fresh measures to boost security in the French port - including extra sniffer dogs and fencing - but critics claimed they were a "sticking plaster".
Options to relieve the chronic traffic on the M20 are being considered but specific locations are yet to be confirmed.
Laws including new powers to tackle illegal working will be fast-tracked, while Britain and France plan to put on flights to return migrants to their home countries.
However, Mr Cameron admitted: "This is going to be a difficult issue right across the summer."
The ominous prediction comes as police and social services are already struggling to cope with the impact of the events across the Channel, while businesses, lorry drivers, holidaymakers and residents have been hit by the resulting travel chaos in Kent.
It came after a fourth night of disruption at the terminal in northern France, while migrants' desperation to reach Britain was laid bare in an extraordinary picture showing two clinging to the top of a lorry as it arrived at Folkestone in the early hours of Friday.
There was more disruption in Calais yesterday as striking ferry workers reportedly burned tyres.
Speaking in Downing Street after chairing a meeting of the Cobra emergency committee, Mr Cameron said no action would be ruled out. He has assembled a team of senior ministers to lead the response.
Britain will work "hand in glove" with the French to tackle the problem, the Prime Minister said.
"The situation is not acceptable and it is absolutely this Government's priority to deal with it in every way we can," he said.
"We have got people trying to illegally enter our country and here in Britain we have got lorry drivers and holidaymakers facing potential delays."
The new Immigration Bill, which includes powers to tackle illegal working and abuse of the asylum system, will be "sped up" and introduced as soon as MPs return to Parliament after the summer break, Downing Street said.
Efforts to reduce the number of migrants in Calais - estimated to be as high as 5,000 - will also be stepped up. A No 10 spokeswoman said: "That includes stronger cooperation on returns, with UK funding and joint flights to countries like Sudan."
Britain will provide more fencing to secure the platform at Coquelles in addition to equipment already promised. More border force search and dog teams will also be deployed.