Immigrants who take part in protests against British troops could be denied citizenship of this country under controversial new Home Office rules.

The Home Secretary, Alan Johnson, will launch a consultation tomorrow on a new points-based system for would-be migrants according to their behaviour, as well as skills and qualifications.

Mr Johnson, writing in the News of the World, said: "Bad behaviour will be penalised, and only those with enough points will earn the right to a British passport."

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While he did not explicitly point to those who take part in anti-war demonstrations, the newspaper reported that this would be included in examples of "bad behaviour".

But there was confusion over the policy last night, as the Home Office appeared to backtrack on whether protesters would be penalised.

An aide to Mr Johnson said the Home Office was consulting on what constituted bad behaviour, but refused to comment on the issue of protesters.

Earlier this year, troops on a homecoming march in Luton were jeered by Muslim protesters carrying placards that read "Butchers" and "Animals". However, there was no suggestion that the protesters were, in fact, immigrants, so the alleged rules would not apply in any case.

While inciting hatred is a crime, the suggestion that taking part in an anti-war protest could be a bar to a British passport would be highly controversial and draw accusations of pandering to the right.

The new rules would also see the period for which foreigners have to work in the UK before becoming eligible for citizenship doubling from five to 10 years. Applicants from outside the EU are already subject to a points-based system that covers skills, but the tougher rules would sever the "link between temporary work and becoming a permanent UK citizen", Mr Johnson wrote.

"Already we require that people earn the right to become citizens by paying taxes, speaking English and obeying the law," Mr Johnson added. "Tomorrow I will go even further, unveiling my new citizenship proposals which will require that people earn points for, among other things, their skills, their job and their qualifications."

As Mr Johnson risked charges of playing tough on immigration, the Foreign Secretary, David Miliband, stoked the row over the Conservative Party's new alliance with the far right in Europe. Mr Miliband issued a thinly veiled attack on a Polish politician accused of anti-Semitism.

The Foreign Secretary said David Cameron's decision to support Michal Kaminski as leader of the Tories' new Euro-grouping had provoked "real cause for concern" among Britain's Jewish community. Mr Kaminski, a member of the far-right Polish Law and Justice Party, has denied claims that he opposed an apology by his countrymen in 2001 for the massacre of hundreds of Jews in Jedwabne in July 1941.

The Foreign Secretary, the son of Jewish refugees of the Holocaust, said: "David Cameron has shown little appetite for tough decisions in his career to date. On this rare occasion, he has decided to expend some serious political capital. And on what? On supporting a man like Michal Kaminski for a position of influence in the European Parliament over a moderate and loyal member of his own party.

"It has given key communities in Britain real cause for concern. Against the best advice of foreign leaders and British business, he drove the Tories out of the mainstream and into the right-wing margins of Europe. This reversion to the right-wing extremes of his own party should give people a strong sense of what both he and his party believe in, and it has nothing to do with the best interests of Britain."

Mr Kaminksi has insisted he is not anti-Semitic, and claims he has spent "a lifetime of work supporting Israel and the Jewish community in Poland".