HOME Secretary Alan Johnson called today for police to respond to questions about the monitoring of convicted rapist Peter Chapman as he expressed his absolute sympathy for the family of Ashleigh Hall.

Mr Johnson said lessons needed to be learned following the terrible tragedy of the murder of 17-year-old Ashleigh by Chapman, a convicted sex offender she met on a social networking site.

Chapman was jailed in 1996 for raping two prostitutes and was also suspected, though never charged, of carrying out other rapes and sex attacks against young women.

Merseyside Police confirmed last night that they waited nine months to put out a national alert after Chapman - who was still on parole - could not be contacted over a traffic offence.

Officers visited his house in Liverpool in January last year, but it took until September for the full alert to be issued.

Asked on BBC Breakfast about how Chapman had come to evade the police in this way, Mr Johnson said: "I think it is right that Merseyside Police actually respond to that.

"We have some of the most stringent laws governing sex offenders in the world and this terrible tragedy... we have to learn lessons from this, whether that is an issue about the monitoring of Chapman - and there is certainly an issue there - whether we need to do more, we have got this Child Exploitation and Online Protection Centre that is a very, very powerful organisation that we are seeking to give more powers to tackle this... whether we need to do more there as well...

"I just feel absolute sympathy for Mrs Hall and the family of this poor young girl."

Asked about how a convicted rapist could use social networking sites in this way, Mr Johnson said: "There is an idea we are talking to the Americans about - when you log on, if you are a convicted sex offender, that actually there is a way of flagging that up.

"What our people in the child protection and online protection agency do is actually go online themselves to actually try and lure in these people.

"Whether we could get the technology to flag up when they are online is something we need to look at.

"We do have very stringent measures and we do actually need to ensure... as Mrs Hall herself was saying, that parents need to be very careful about what their children are doing online.

"I think Facebook also are looking at the lessons from this."

Mr Johnson's remarks were made as Facebook urged internet users today not to meet strangers they have only had contact with online after the kidnap, rape and murder of Ashleigh.

Yesterday, Chapman, who admitted the charges, and was also suspected of other attacks, was jailed for life and told he would serve at least 35 years.

Ashleigh's mother, Andrea Hall, also warned of the dangers of social networking sites and questioned why Chapman was free to attack her daughter.

In a statement, Facebook said it was deeply saddened by Ashleigh's death.

The statement urged people "not to meet anyone they have only had contact with online unless they are certain they know who they are, as there are unscrupulous people in the world with malevolent agendas".