Republican senators introduced a bill Wednesday to close loopholes in U.S. immigration law that have allowed thousands of minors to be subjected to child marriages.

The move follows a report by the Senate Homeland Security Committee that found the federal government approved requests from thousands of men to bring child brides or fiancées into the country over the past decade, in part because the Immigration and Nationality Act doesn't set minimum age requirements in such visa requests.

Under that law, a U.S. child can petition for a visa for a spouse or fiancé living in another country, and a U.S. adult can do the same for a minor spouse or fiancé living abroad, the report found.

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The legislation, introduced by the committee's chairman, Ron Johnson of Wisconsin, and Joni Ernst of Iowa and Tom Cotton of Arkansas, would set a minimum age of 18 for spouses or fiancées in visa applications.

"A visa to enter the United States is a privilege, and this straightforward reform will help close a loophole that can lead to the abuse and exploitation of children,” Johnson said in a statement. “I hope my colleagues will join me to advance this commonsense legislation.”

The legislation would not completely end child marriage in the United States because most states allow citizens under 18 to marry, but often with judicial or parental consent. New Jersey and Delaware are the only states that prohibit marriages involving those under 18, having passed bans last year.

From 2007 to 2017, Citizenship and Immigration Services approved more than 5,500 petitions by adults to bring minor spouses or fiancées into the country, and granted nearly 3,000 requests by minors trying to bring in older spouses or fiancés, the committee's report said. Girls were the minors in 95 percent of the cases.

The agency also approved petitions for people with significant age differences, the report found. In one case, a 71-year-old U.S. citizen requested a visa for a 17-year-old spouse from Guatemala, and in another, a 14-year-old sought entry for a 38-year-old from the Democratic Republic of the Congo. Both visa requests were granted. The USCIS approved 149 petitions involving a minor with an adult spouse or fiancé who was over 40, the report said.

In reviewing such visa petitions, Citizenship and Immigration Services only considers whether the age at marriage violates the laws "of the place of celebration" or the U.S. state in which the couple plans to live, the report said. But data entry errors and faulty processes at the agency — particularly its reliance on a paper-based immigration benefits system — prevent the applications from getting thoroughly vetted, the report found.

In addition, the State Department, which is responsible for issuing the visas, rarely rejects petitions approved by the immigration agency, the report said.

The findings prompted advocates to demand Congress take action to close the loopholes in the immigration system that allow such child marriages to continue in the United States.