Eurotunnel says hundreds try to stow away each night
It is the third attempt in less than a week, and the tunnel's operator Eurotunnel is blaming it on the proximity of the Red Cross refugee camp near Calais.
Shadow Home Secretary Ann Widdecombe told the BBC that the proximity of the Sangatte centre to Calais was an "immense encouragement" to asylum seekers making daily attempts to enter Britain.
In a separate incident another 40 illegal immigrants were found in the back of a lorry at the port of Dover, in Kent, on Sunday.
With regards the attempts by refugees to enter the UK via the Channel Tunnel, Miss Widdecombe said: "We have to ask why people, who are in a perfectly safe country such as France, still want to smuggle themselves here?"
She said refugees denied asylum in France knew they would be sent home, while the chances of failed applicants being forced to leave the UK were "very, very small".
"We have got a system that is not helping the genuine refugee, but is helping the person who does not seriously need it," she said. "Now what sort of chaos is that?"
Camp controversy
Eurostar passenger services were delayed for several hours on Saturday evening and freight services suspended overnight, after the illegal immigrants were caught inside the Eurotunnel compound at Coquelle.
Earlier, the UK Home Secretary, David Blunkett, intervened in the row about the camp, reportedly saying it was hindering Britain's efforts to stop illegal immigration.
The Sunday Telegraph said that Mr Blunkett had asked the French Government to close the camp.
The paper reported that the home secretary would prefer to see a series of much smaller units inland which could house the refugees.
But a Home Office spokesman declined to confirm that Mr Blunkett had specifically asked for Sangatte to be shut.
He said the home secretary had spoken very recently with the French Interior Minister Daniel Vaillant about Sangatte and migration.
The spokesman added: "Ultimately its location is a matter for the French, although we do believe its location is not helping the situation at the Eurotunnel at Coquelle."
Fines
On Sunday 39 Sri Lankans and an Indian were found in the back of a German lorry which had arrived at Dover on a cross-Channel ferry from Calais.
A 29-year-old German lorry driver has been arrested on suspicion of people smuggling and was being held in custody at Dover police station for questioning.
Last Wednesday, 44 Afghans discovered trying to walk through the tunnel were thought to have broken into the Eurotunnel compound after leaving the Sangatte camp.
An 80-strong group of illegal immigrants, also thought to be from Sangatte, tried unsuccessfully to break into the same compound last Thursday.
Eurotunnel is threatened with sizeable fines for every illegal immigrant who gets through the elaborate security measures.
Hundreds of people have managed to escape detection on the French side and enter Britain in trucks, on board ferries and through the tunnel on trains.
The company has begun legal action in the French courts to force Sangatte's closure.
It wants the French authorities to shut down the camp because immigrants are targeting its services.
In the UK the company is fighting Home Office plans to fine it £2,000 for every illegal immigrant found on its services.
The rules currently apply to airlines, ferry operators, road hauliers and other freight train operators, and the government wants them to be extended to Eurotunnel.
Eurotunnel argues that is unfair, saying it is a private transport company, not a frontier control point, and already prevents thousands of immigrants entering the UK illegally.