The Liberal Democrats have become the first major political party to call for long-term illegal immigrants to be offered an amnesty and the chance to gain British citizenship. As many as 600,000 people living in "a perpetual twilight world" could earn the chance to regularise their status after 10 years under policy proposals adopted at the party's conference in Brighton.
Both Labour and the Tories oppose the move, arguing it could encourage more migrants to head to Britain, but has been supported by trade unions and immigrant groups.
Under the Liberal Democrat plans such migrants would be eligible for citizenship after 10 years if they had no criminal record, proved their commitment to the United Kingdom and sat an English and civics test.
Nick Clegg, the party's home affairs spokesman, conceded that it would face criticism on the issue. But he argued: "I do not think we should ever be cowed into silence by fear of controversy." He said politicians could no longer ignore the subject, adding: "To do so does nothing to solve the problem and merely helps those traffickers who currently exploit the system."
The leadership comfortably defeated an attempt to remove the qualifying period for illegal immigrants by critics who argued that 10 years was too long.
It also won support for plans to create a national border force, reintroduce exit checks at ports, increase English lessons for newcomers and raise fees to businesses for work permits.
Mr Clegg said: "The issue of immigration has become the dog-pit of British politics – a place where only the political rottweilers are happy to enter."
He called for the debate to be governed by "facts not prejudice, fairness not vitriol", adding: "While others pander to fear, we are a party that stands up for the values of freedom, tolerance and diversity."
During the immigration debate, Kate and Gerry McCann's former spokeswoman made a passionate appeal for passport checks to be reintroduced for people leaving the country.
Justine McGuinness, a former Liberal Democrat parliamentary candidate, said: "If we want to protect our children we have to make sure that children cannot be moved out of Europe, as well as in."
The call for an amnesty was criticised by Liam Byrne, the Immigration Minister, who said: "I believe those here illegally should go home, not go to the front of the queue for jobs and benefits."
Damian Green, the Conservative immigration spokesman, said: "These proposals will encourage people to break the law and enter the UK illegally."
Habib Rahman, chief executive of the Joint Council for the Welfare of Immigrants, praised the Liberal Democrats for promoting "a reasonable debate on an issue which is all too often the subject of emotive soundbites". But he added: "The 10-year threshold he is suggesting for entry into a regularisation programme is too high to be really useful in offering protection to the majority of undocumented migrants or cutting deportation costs."
The Liberal Democrats also risked the wrath of teachers and nurses by calling at their conference for the generous pensions given to public sector workers to be reconsidered. Danny Alexander, the work and pensions spokesman, warned of the growing gulf between the "high quality" pensions enjoyed by many state employees and those available to the employees of private companies.
Charles Kennedy, the former leader, who is still adored by wide sections of the party, won rapturous applause with a rallying call to the party.
He said: "The challenge, colleagues, for us from now until the next election is to take the fight to our opponents. My message to you, quite simply and whole-heartedly, is to be self-confident about it, to confront our critics and to put the case across boldly and with rigour."Reuse content