The defence of provocation in murder cases looks set to be scrapped.

The Government is proposing a defence which could see killers escape a murder conviction by proving they were motivated by "words and conduct" which left them "seriously wronged".

If a jury accepts that partial defence in a murder trial the defendant can be convicted of manslaughter instead, and receive a much lower sentence.

The proposals - which have already taken more than four years to draw up - will also create a new partial defence of "fear of serious violence".

It would mean, for example, that men and women facing domestic violence could argue they were forced to kill their tormentor.

However, the Ministry of Justice said the law would be changed to make it clear that someone who discovers their partner is having an affair would not be entitled to argue they had been "seriously wronged".

Men and women who suffered a "slow burn" of domestic violence over a period of time could also use one of the partial defences under the proposals, overturning current law which requires them to have acted on the spur of the moment.

Current laws have made it too easy for men to kill their wives and claim they were provoked by the victim's infidelity, but at the same time restricted the use of partial defences by women with abusive partners, government documents said.

Justice minister Maria Eagle said: "If you look at recent cases, it seems clear that judges and juries have been trying to stretch the current law.

"With these changes, the law will be clearer."

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