Yet more asylum seekers broke into Frethun on Friday night

Stow-away attempts have become more frequent at the Frethun freight terminal since security was tightened at the Eurotunnel terminal and Calais ferry terminals because of the same problem.

EWS, which takes over the operation of UK-bound SNCF trains once they reach Kent, has called for more action from the authorities on both sides of the tunnel.

Transport Secretary Stephen Byers was asked generally about the problem at the House of Commons Transport Committee on Friday evening.

He said it had been continually pointed out to the French that they had a duty to secure the area around the tunnel.

Liberal Democrat home affairs spokesman Simon Hughes agreed better security was the short-term solution.

But he added: "It is not until there are European Union procedures for dealing with would-be asylum seekers that the longer-term solution can be found."

1,700 cancellations

EWS said it has had to cancel 1,700 services since November, and is losing �500,000 a week because of cancellations.

It had initially hoped to run 15 services in each direction through the tunnel each day, but has had to reduce that number to five.

Spokesman Graham Meiklejohn said: "If we get one service through on one night at the moment we consider that to be good.

The solution to this crisis is simple - the French authorities must provide the proper level of security required

EWS spokesman

"British businesses are feeling the pain from this. The situation cannot continue. If it does for much longer there will be no customer base to return to."

Mr Meiklejohn said the UK Government must put more pressure on the French authorities to sort the problem out.

And he said France must provide the proper level of security required to operate services 24-hours a day.

The persistent attempts to access the tunnel have led to various calls - all so far thwarted - for the closure of the Red Cross Sangatte refugee centre near its French entrance.

The BBC's Jon Sopel, at the tunnel, said one of the problems was that anyone arrested on the tracks was simply returned to the centre.

"You can be absolutely sure they will try again the next night, and the night after that, until eventually they get to Britain."