Baroness Warsi pleaded with cabinet colleagues to drop what she warned would be seen as a "racist" policy when they discussed curbs on migrants bringing family members to live with them in Britain.
The row exploded when Theresa May, the Home Secretary, proposed that UK citizens earning less than £40,000 should not be allowed to bring in a foreign wife or husband, The Independent has learnt. Lady Warsi, the Conservative Party co-chairman and the first Muslim woman to sit in the Cabinet, warned that such a policy would amount to a "whites only" entry rule, with family members living in the Punjab having no chance of getting to this country. Cabinet colleagues say she warned bluntly that such a policy would be viewed as "racist".
The Tory peer, whose own father came to Britain from the Punjab, mounted a successful rearguard action against the Home Office plan after winning the backing of Nick Clegg and his fellow Liberal Democrat ministers. Ms May was forced to back down and announced a much lower income threshold of £18,600 last week, with a further £2,200 for each child.
Lady Warsi's office declined to comment. But one ally said: "Sayeeda does feel passionately about this issue." A Whitehall source confirmed: "She fought her corner very strongly. Other ministers took what she was saying very seriously." Last month, the Tory co-chairman raised eyebrows by saying that a small minority of Pakistani men saw white girls as "fair game". Nine Muslim men had been found guilty of grooming girls for sex in Rochdale. Greater Manchester Police had played down claims about a racial element.
Another cabinet dispute over immigration looms over a plan to exclude foreign students from the official figures. This is being floated by David Willetts, the Conservative Universities minister, and Vince Cable, the Liberal Democrat Business Secretary, who are said to be arguing that students should not be counted because the vast majority only stay in Britain temporarily. The move would boost David Cameron's prospects of meeting his pledge to reduce net migration to under 100,000 a year. It is currently running at 250,000.
But it is being opposed by the Home Office. Damian Green, the Immigration minister, has insisted that the Government is on course to meet its target without "fiddling" the figures. He told BBC2's Newsnight programme that ministers could not "redefine" its way out of a problem. "Changing the thermometer does not change the temperature," he said.
Yesterday, Mr Green turned his fire on Labour as the party began to launch a tougher stance on immigration. He told The Independent: "This feels to me eerily reminiscent of Gordon Brown talking about British jobs for British workers. Unless they are proposing to rewrite the rules of the European Union they could be promising to deliver in an area where action is least likely."
l Moves to increase the penalties for people-trafficking will be announced by the Home Office today. The Attorney General will gain the power to appeal against what are viewed as lenient sentences for criminal gangs bringing in overseas nationals.
Family fortunes: What you must earn
Immigration earning rules
Under the new rules, any foreign national who wants to bring a spouse to Britain will have to earn at least £18,600.
The figure rises if the couple have children – someone applying to bring in three children needs to earn £27,200.
Previously there was no minimum income requirement.