London: The Home Office is looking into reports that hundreds of mentally-ill criminals have been released from secure mental hospitals without being considered for deportation.

The Sun newspaper said yesterday that police were trying to track down 500 foreign nationals, including rapists, murderers and child sex offenders, who have been released from mental hospitals.

The Home Office said it was not able to comment precisely on the newspaper report because it does not know the exact numbers of people who may be involved. It said an investigation has begun to get hold of the data.

"Historically there has been no automatic system to record the nationality of mentally-ill offenders," a ministry spokesman told reporters. "Officials are going through the files to see who might be eligible for deportation." This latest news piles pressure on the Home Office which has been dogged by negative publicity for months over a row that erupted when it was revealed that 1,019 foreign criminals were not considered for deportation after the end of their jail term. Newspapers have detailed every new twist, from illegal immigrants working as cleaners in the immigration department to allegations officials ran a sex-for-visas racket.

Attention on the failings of one of the country's biggest and most diverse government departments has been intense. The Daily Mirror newspaper branded the department the "Ministry of Mayhem".

When Tony Blair sacked Home Secretary John Reid's predecessor Charles Clarke earlier in May, he said the release into the community of foreign prisoners highlighted failures at the Home Office. On Wednesday, Reid, was forced to apologise to MPs for giving out incorrect figures relating to released prisoners who have been returned to jail to await consideration for deportation.

Critics argue the changes by Reid at the Home Office do not go far enough and that the department has become too unwieldy.