British citizenship can be revoked from immigrants who "seriously prejudice" the UK's interests, under new laws coming into force on Tuesday.

The new powers come under section four of the Asylum, Immigration and Nationality Act 2002.

Applying only to those with dual nationality, they could lead to undesirables being deported from the UK.

Home Secretary David Blunkett said British citizenship was a "privilege" which should not be acquired by deception or abused by people "acting against the UK's vital interests".

He would thus "prepare a case" under the new laws to take action against anyone who had acted in a way which was deemed incompatible with holding British citizenship.