Conservative Party security spokesman, Patrick Mercer is to introduce a Bill in parliament intended to shift the legal balance in favour of the householder protecting himself from burglars.

Britains top police officer Metropolitan Police Commissioner Sir John Stevens spoke out on Saturday saying householders should get the right to defend themselves in their home and arguing for the law to give anybody harming a burglar the presumption of "acting lawfully" rather than the other way round, even if the burglar was killed.

Presently, the law now only allows householders to use "reasonable force" to defend their families and property.

Patrick Mercer's Bill would offer freedom from prosecution to anybody in their own home taking any action against an intruder, provided it is not "grossly disproportionate". Mercer won the right to introduce the Bill after coming top in a ballot for Private Members legislation.

Significant parliamentary time for the Bill is expected to be given within a few weeks.

The issue of what force may be "reasonable" was plunged into the spotlight when Tony Martin, the Norfolk farmer was jailed for shooting dead a 16-year-old burglar. But Sir John Stevens said on Saturday although the case had raised the issue of self defence he though it was not a good example because Martin had shot the suspect as he was running away.

Previous attempts to give householders greater rights to tackle burglars have stumbled in the wake of opposition. Earlier this year, Conservative MP Roger Gale failed in his move to gain legal protection for people who believed they had acted in reasonable self-defence against intruders.

Green Party concerns have been raised about Sir John's proposals. Home affairs spokesman Hugo Charlton said Sir John Stevens's proposal, "Could easily lead to a country where burglars enter your house prepared not only to steal your TV, but to kill or be killed. Promising householders immunity over killing seems like a sure way to up the stakes in the burglar's mind."