A leading union official has called for a debate on the possible amnesty of half a million illegal migrant workers.
Jack Dromey, deputy general secretary of the TGWU, said the government should adopt "sensible" policies that avoid making criminals out of law-abiding economic migrants.
He told the BBC: "The economy needs migrant labour. They are the backbone of the service economy, cleaning, catering, looking after the old, the sick and the dying, and of food and agriculture.
"Yes, it is true that there are probably half a million here without documents. The question is what we do about that.
"What we need, therefore, is a sensible approach which does not criminalise those good men and women.
"You can't deport half a million workers - who would clean, who would cook, who would pick in our fields?
"The time has come for a debate around an amnesty for those workers," he reasoned.
The issue of illegal immigration dogged the government this week after it emerged five illegal migrants from Nigeria had worked as cleaners at the Home Office for three years, contrary to initial claims that they were nabbed on their first day.
Immigration minister Tony McNulty has admitted the number of illegal immigrants could be anywhere between 310,000 and 570,000.
Shadow attorney general Dominic Grieve said an amnesty would present many problems.
Meanwhile, Labour peer Lord Foulkes of Cumnock said he was confident that ID cards would help identify illegal immigrants.