Federal authorities have arrested 170 immigrants who came forward seeking to sponsor migrant children in government custody, Immigration and Customs Enforcement officials said.

ICE said Tuesday that the arrests were of immigrants suspected of being in the United States illegally and took place from early July to November. They were the result of background checks conducted on potential sponsors of unaccompanied migrant children placed under the care of the Department of Health and Human Services.

Nearly two thirds of those arrested — 109 in total — had no criminal record, the agency said. Another 61 of those arrested did have criminal records, but ICE did not specify the crimes and said it could not break down convictions by violent and nonviolent offenses.

The arrests follow a move by President Donald Trump's administration earlier this year that allowed immigration authorities to examine the criminal background and legal status of anyone who steps forward to sponsor unaccompanied migrant children — usually parents or close relatives already in the U.S. — as well as any other adults living in their home.

That rule allowed ICE to collect biometric data, including fingerprints, of the sponsors as well as other adults in the home.

Just under 80 percent of people screened by ICE during the sponsorship process showed results that they were not in the country legally, the agency said.

The number of arrests was first reported Monday in the San Francisco Chronicle.

Advocates are worried that the rule would lead to arrests of people coming forward and leave a growing number of children in government shelters or foster care.

Bills have been introduced in the U.S. Senate and House of Representatives that would prohibit ICE from using the information obtained via sponsor background checks for the purposes of immigration enforcement.

Sen. Kamala Harris, D-Calif., who introduced the Senate bill, criticized the arrests on Twitter.

"A natural consequence of these arrests is that these children have nowhere to go," she tweeted Tuesday afternoon.

When asked to comment on advocates' concerns, an ICE spokesperson said "non-criminal" immigrants are at times "immigration fugitives," have been previously removed from the country or have pending charges against them and that it would be "speculative" to assume the government agency housing the children would have placed children in the custody of those individuals.

The latest numbers follow the arrest in September of 41 people who had similarly tried to sponsor migrant children following the administration's change.