Vince Cable today attacked Tory colleagues for launching a "stupid and offensive" crackdown on illegal immigrants and accused them of being obsessed with migration figures.
The Business Secretary said Immigration Minister Mark Harper's decision to send vans bearing the message "go home, or you'll be picked up and deported" round London was designed to create fear among the public.
He rubbished "misleading" targets to reduce net migration and insisted Britain did not have a vast problem with illegal immigrants.
He questioned whether illegal immigrants would have enough of a "sophisticated grasp of English" to be able to read the posters on the vans at a distance.
"I think it is offensive. It is designed, apparently, to sort of create a sense of fear (in the) British population that we have a vast problem with illegal immigration.
"We have a problem but it's not a vast one. It's got to be dealt with in a measured way dealing with the underlying causes."
Asked about the damning criticism about the accuracy of migration figures by the Public Administration Select Committee today, Mr Cable said: "We are not a totalitarian state. We don't count every single person but actually it's quite difficult being an illegal immigrant in Britain. You can't work, certainly legally, you can't have access to benefits. So, the idea that there's some vast, hidden army of people, is almost certainly completely wrong.
"The argument about those numbers, which was raised this morning by a select committee, it only really matters if you are pursuing some target. There's this sort of net immigration figure, which the Conservatives are very preoccupied by.
"It's not a government objective, make it absolutely clear.
"This idea that you are pursuing a net immigration figure is very misleading because, amongst other things, the largest number of people counted as immigrants are overseas students, who are not immigrants, they are visitors but under the United Nations classification they are regarded as immigrants, but they are good for the country.
"So obsessing about this net immigration number is not helpful."
Shadow Home Secretary Yvette Cooper said: "There is now complete confusion over whether these ill judged ad vans are actually government policy or not. As we have made clear for some time, this is a cynical stunt from a Government that's not getting the basics right on immigration.
"With no consultation with local communities the Government has simply caused offence with these ill-judged ad vans. They seem to be aimed at lost Tory voters rather than a sensible strategy to tackle illegal immigration
"Now Cabinet Ministers are openly disagreeing. Vince Cable is right they are stupid, but why then is the Government sticking by them, instead of getting the basics right with a proper plan for efficient border enforcement?
"We need a grown up debate about what's important and making immigration work for all. Instead we have ludicrous posters and a Home Office practising stupid politics."