Adults who befriend children in person or via the internet with the intention of abusing them will face five years in jail under a government crackdown on sex offenders.

The new offence of sexual "grooming" will enable police officers to intervene and arrest a suspect before any sexual activity takes place.

New sex offences include:

Bestiality Voyeurism Sexual interference with human remains

Home Secretary David Blunkett told MPs the new offence would "protect children from the insidious use of the internet by paedophiles".

Mr Blunkett told MPs that anyone found guilty of having sex with a child aged 12 or under would be charged with rape with a maximum penalty of life in prison.

Inducing a child to take their clothes off - for "modelling", for example - will carry a maximum penalty of 10 years jail if no physical contact was involved, and 14 years if there was direct contact.

Blunkett: reform is badly needed

There will also be a shake-up to the rape laws - with a new test of "reasonableness" applied to sex cases where consent is an issue.

A victim would be considered to have been unlikely to have said yes to sex if they were unconscious, abducted, threatened by fear or force and unable to communicate their decisions because they are physically disabled.

A defendant would have to prove they had taken "reasonable action" to ensure that the other person was willing to take part in the sexual act.

Sex outdoors

There is to be no separate offence of "date rape" but administering drugs or other substances with intent to stupefy a victim so they can be subjected to an indecent assault without consent will carry a 10-year sentence.

They are also aimed at increasing conviction rates for rape - which currently run at one in 14.

The laws about sex in public are also set for change, with those covering homosexuals brought in line with those covering heterosexuals.

Sarah Payne's murder prompted calls for tougher laws

Outdoor sexual activity will not be a criminal offence, as long as it is away from unwilling witnesses.

As a whole, Mr Blunkett said the new reforms would make laws that are "archaic, incoherent and discriminatory" into laws "fit for the 21st century".

The parents of murdered schoolgirl Sarah Payne campaigned for the public to be allowed to know where sex offenders live.

That change will not happen but changes proposed would mean all 18,500 people on the Sex Offenders Register have to re-register their details with the police annually, instead of every five years as at present.

Failing to comply with that requirement could also carry a five-year jail term.

Changes to existing laws will apply in England, Wales, Northern Ireland, while measures contained in a new Sex Offences Act will apply across the whole of the UK.

Under the plans, there will be new offences covering bestiality, voyeurism and sexual interference with human remains.

New measures against child prostitution are also planned, as well as a review of laws on adult prostitution, which Mr Blunkett said was bedevilled by "mafia-style criminality".

Mr Blunkett told MPs: "Sex crimes can tear apart the fabric of society."

Stopping exploitation

The measures have been trailed as helping to give the UK the "toughest child protection laws" anywhere in the world.

Conservative shadow home secretary Oliver Letwin welcomed the general principles of the new plans.

But he promised his party would put the measures under "close scrutiny".

Liberal Democrat home affairs spokesman Simon Hughes also said the chance to reform "outdated" laws should be fully used.

"Children must be effectively protected from exploitation by bringing the law on sex offences into the 21st century," said Mr Hughes.

Human rights groups Liberty welcomed many of the proposed changes to the laws.

Among its concerns were that the new "grooming" offence could see people prosecuted because people were "second guessing" their thoughts.