“How did the judge determine that a 12-year-old was ready for marriage?” she asked. She noted that having sex with a 12-year-old girl who is not one’s wife is considered statutory rape under Malaysian law.

“Yet once you do it under the name of marriage, she is no longer a minor? Her body has suddenly transformed into an adult body?” Ms. Ratna said. “You would be charged under the law on statutory rape but get permission from the court and suddenly it’s O.K. to have sex with a 12-year-old.”

Sharmila Sekaran, chairwoman of Voice of the Children, a rights group in Kuala Lumpur, also said the government should outlaw child marriage.

“This should not be happening regardless of the fact that the parents had consented. I don’t think parents should be allowed to consent for children the age of 12,” she said. “There has been research done which shows that children at the age of 12 are not sufficiently mature to understand their role within a marriage and certainly in terms of becoming parents; they themselves are still children.”

Ms. Sharmila added that studies had found that young girls who become pregnant and their babies faced greater health risks than older women.

But Nazri Aziz, the government minister responsible for legal affairs, said the government had no plans to amend the law regarding the minimum legal age of marriage “because it concerns Islamic law.”

He said the government could not pass any law that would be inconsistent with Islamic law.

The United Nations report included Malaysian census data showing that in 2010, about 1.4 percent of married women, or more than 82,000, were 15 to 19, up from 1.2 percent, or about 53,000, in 2001.

The researchers interviewed six girls and one boy who married below the legal age and found that their reasons for getting married included to avoid premarital sex, which is forbidden under Islam; to avoid being arrested for khalwat, an Islamic offense in which unmarried men and women are found together in “close proximity”; coercion by family elders; and pregnancy.