Afghan President Hamid Karzai said Saturday he has ordered the ministry of justice to review a law that critics say will make it illegal for women to refuse sex with their husbands.

Karzai said the law, which has already been passed, could be sent back to parliament should it contain stipulations that contradict the Afghan constitution or the tenets of Shariah law.

"I ordered the justice minister to review the law, and if there is anything that would contravene the country's constitution or Shariah law or the freedom our constitution gives to Afghan women, without any doubt there will be changes in it, and again it will be sent to the parliament of Afghanistan," Karzai said during a news conference. "Measures will be taken."

The law applies to Afghanistan's Shiite community, which makes up between 10 to 20 per cent of the country's population.

The United Nations Development Fund for Women argues that the law "legalizes the rape of a wife by her husband."

One of the most controversial articles in the law, Article 132, appears to legislate the frequency of sexual intercourse among Shiite couples.

The article says a husband has the right to have sex with his wife every fourth night unless she is ill.

During his Saturday news conference, Karzai said he had studied the law and that "I don't see any problems with it."

He accused Western media outlets of misinterpreting the law and pointed out that, despite the fact that it restricts a woman's right to leave her home, it does allow exceptions during emergencies.

The law has led to outrage among many Western politicians.

U.S. Secretary of State Hillary Rodham Clinton has spoken to Karzai about the law, and U.S. President Barack Obama called the law "abhorrent."

Prime Minister Stephen Harper hailed the review as a "good step" but said the Canadian government would continue to pressure Karzai about the law.

"The involvement of the international community (in Afghanistan), particularly Canada and our NATO allies, is based on the pursuit of very fundamental values in opposition to the kinds of values that the Taliban stood for," Harper said during a news conference at the close of this weekend's NATO summit. "And if we drift from that there will be a clear diminishment in allied support for this venture."

Women's rights in Afghanistan have been a concern to Western nations since the Taliban regime that ruled Afghanistan in the late 90s severely restricted women's movements.

Women were prohibited from attending school, holding a job or appearing in public without a male escort.

Now, schools are open to girls and women own businesses and run in elections. Eighty-nine of 351 parliamentarians are women.

With files from The Associated Press