Afghanistan has enacted a new legislation empowering men of Shia sect of Islam to deny their wives food and sustenance if they refuse to obey their husbands' sexual demands, a media report said on Saturday.

The new final draft of the legislation also grants guardianship of children exclusively to their fathers and grandfathers, and requires women to get permission from their husbands to work, The Guardian reported.

"It also effectively allows a rapist to avoid prosecution by paying 'blood money' to a girl who was injured when he raped her," the report said quoting US charity Human Rights Watch.

In early April, US President Barack Obama and British Prime Minister Gordon Brown joined an international chorus of condemnation when the earlier version of the law legalised rape within marriage.

Although Afghan President Hamid Karzai appeared to back down, activists said the revised law still contained repressive measures and contradicted Afghanistan's constitution and international treaties it is signed up to.

According to the report, the new law has been backed by the hardline Shia cleric Ayatollah Mohseni, who is thought to have influence over the voting intentions of some Shias, who make up around 20 per cent of the population.

Karzai has assiduously courted such minority leaders in the run up to next Thursday's election, which is likely to be close, a poll indicated on Saturday.