Immigration officials use thermal imaging to look for stowaways

One route which has been used by would-be asylum seekers is the Belgian port of Zeebrugge.

Almost a million lorry journeys a year pass through the port and the authorities there used to regularly find up to 80 people a week trying to get to Britain.

But a combination of new technology and a more pro-active approach by the UK Government - aiming to stop illegal immigrants before they reach Britain - appears to be paying dividends.

The only thing they could say was 'boat' and 'England' Helmut Wallgrave Shipping firm manager Asylum applications down in UK

British taxpayers have paid for equipment at the port designed to detect people trying to stow away, such as thermal imaging devices and vibration monitors that are so sensitive they can detect the heartbeat of a mouse.

Helmut Wallgrave, the general manager of shipping company Dartline, which operates three sailings a day from Zeebrugge to Dartford in Kent, said the problem has not gone away but had been reduced.

"A couple of days ago we had some people wandering around on the terminal, probably after coming out of a trailer, and the only thing they could say was 'boat' and 'England'," he told BBC Radio 4's Today programme.

"The tight security has proved to be very successful considering the number of illegals we intercept now compared to the past."

'Lives at risk'

But Mr Wallgrave believes the real solution to the problem lies in tackling it in people's country of origin.

"I think Europe and the UK should work together and try to convince these people not to start to travel to the UK because it's a rough ride.

"They put their own lives at risk, the lives of their families, relatives and children and when they come to the UK. It's not the land of honey and milk, it's much worse than they expected," he said.

While the numbers of people coming through the traditional entry points at ports and the Channel Tunnel may be down, there remains anecdotal evidence that illegal immigrants are entering the UK by other means.

A British lorry driver, who wished to remain anonymous, said the numbers of those trying to get to Britain had reduced but he was convinced many are still successful.

"They are coming in dribs and drabs," he told Today.

"Here at Zeebrugge you see them overnight camping in deserted cars in the car park and then during the day they are taken up to the port by whoever's running them.

The home secretary says improved border security is working

"They always find them in unaccompanied trailers here because it's mostly unaccompanied trailers going across from here. They are still getting through."

The Immigration Advisory Service agrees. Colin Yeo, the charity's head of higher appeals, said the latest figures did not tell the whole picture.

"We believe there are still a lot of people coming here but they are going underground and choosing not to claim asylum.

"As this will mean they are denied benefits, many will end up on the street and resort to crime and begging."

But Mr Blunkett dismissed this idea.

"If that were the case the television pictures, the newspaper articles that we saw this time last year - people leaving Sangatte and coming through the Channel Tunnel, getting out of the lorries in Kent - all of those would still be here.

"People would still be being photographed and on our television screens and they're not because the security and the deterrence we put in are working."