David Blunkett promised yesterday to press ahead with legislation to lock up non-offending psychopaths despite fierce opposition from psychiatrists and concern in Downing Street that his approach could endanger civil liberties.

The home secretary dismissed the complaints from the Royal College of Psychiatrists, the Law Society, and mental health campaigners, as special pleading by professionals just interested in defending themselves rather than doing their best for the community.

In his first public comment on a draft bill published by the Department of Health in June, Mr Blunkett said it was essential to balance the interests of the mentally ill against the need to protect the community from those with dangerous personality disorders.

Under the draft bill such psychopaths would be detained without having committed any crime, even if psychiatrists thought their condition untreatable. At present such detentions would often be unlawful because many psychiatrists doubt whether psychopaths can be treated.

The home secretary said the government could not capitulate on this issue to satisfy professionals who purported to represent the public but "only represented themselves".

The Law Society has warned that the draft bill is incompatible with the Human Rights Act. The Royal College of Psychiatrists said it is racist since Afro-Caribbean men face a disproportionate risk of mistaken diagnosis and imprisonment.

Tony Blair is understood to have told a private meeting of Labour MPs that more time is needed to rethink the reforms.

Mr Blunkett, who was speaking at a conference marking 10 years since Christopher Clunis, who suffered mental illness, killed Jonathan Zito, added: "If I had worried about upsetting professionals rather than representing the public interest, I would have done little in public life ... There has been a tradition of [civil servants] thinking they can have a separate policy to the ministers they serve. They can't."