Government adviser's warning over spot checks for illegal immigrants Home secretary Theresa May is particularly keen to be seen to have got to grips with immigration. Photograph: Getty Images The dispute over the Home Office's controversial spot-check searches for illegal immigrants has escalated, as one of the government's own migration advisers warned that Britain should not adopt the draconian tactics of countries such as Singapore in dealing with the issue. Last week Home Office officials, accompanied by police officers wearing stab vests, conducted a series of checks, mainly at railway stations, as they sought to find immigrants illegally living in the country. It followed the rollout of a number of vans displaying signs encouraging illegal immigrants to "go home" in a pilot that has been widely criticised as heavy-handed. Mark Harper, minister for immigration, defended the government against claims that its spot checks were random by pointing to the number of arrests of suspected illegal immigrants. Yet, speaking to the Observer about last week's crackdown at railway stations, Dr Martin Ruhs, a long-standing member of the government's migration advisory committee, said that he believed the issue was being oversimplified by policymakers. He said: "In liberal democracies generally we don't want to do the kinds of things that are commonplace in Singapore or maybe the Middle East. You have to draw the line somewhere. Different people will draw the line in different places over what is acceptable in how you treat people. Obviously the government has to do something about irregular immigration, but the issue is more complex than many policymakers believe. Some policies have an element of a spectacle - you want to send a signal, and those policies aren't necessarily the most effective. Ruhs spoke out as evidence also emerged of growing tensions within the government, with one senior Liberal Democrat source insisting that there had been no agreement within the coalition to target areas containing a large proportion of ethnic minorities with spot checks, and expressed concern over the direction of travel of Theresa May, the home secretary, and her fellow Tory ministers. The source said: "We would have strong concerns about any suggestion of blanket racial profiling in high ethnic-minority areas. We have not agreed to any such policy as it would be a disproportionate, distasteful and ineffective way to tackle illegal immigration. The home secretary, who is widely believed to have ambitions for the leadership of the Conservative party, is particularly keen to be seen to have got to grips with immigration and is expected to announce further controversial policies this month. The Observer has learned that special advisers working for May have had a series of meals with representatives of the controversial thinktank Migration Watch, which recently predicted that 50,000 Romanians and Bulgarians will come each year for the next five years from 2014 when people there are allowed to work in the UK. Three of May's advisers last had a lunch with representatives of Migration Watch in March, the third such meeting in two years. In another development, the Observer has learned that May has also launched a strongly worded attack on a high court judge in legal documents recently filed in regard to her policy of setting earnings thresholds for people wishing to sponsor the UK visas of spouses coming from abroad. Last month Mr Justice Blake said the policy was a disproportionate interference in people's lives and suggested the income threshold should be lowered from around £18,000 to £13,000. Legal documents submitted by May in appeal, and obtained by the Observer, hit out at the courts by claiming Blake had committed "the error of usurping the role of the democratically accountable decision maker in the formulation of policy." On Saturday night, the shadow home secretary Yvette Cooper said: "The government's policy on illegal immigration seems to be based on headline-grabbing, deliberate controversy and causing offence rather than sensible evidence of what works."