Hundreds of noncitizens were registered to vote in Philadelphia over the last decade, and at least 90 of them actually ended up casting ballots that should never have been allowed, City Commissioner Al Schmidt said Wednesday, adding more fuel to complaints of bogus voting in U.S. elections.

The voters are all self-admitted noncitizens who went back and canceled their registrations later — but not before casting illegal ballots a total of 227 times in elections in 2006 and 2007, Mr. Schmidt said.

He said most of those noncitizens signed up to vote at PennDOT, the state motor vehicles bureau, when they went to get a driver’s license. While legal residents and long-term visitors are allowed to hold licenses, they are not allowed to vote in federal elections — yet thanks to a federal law, the sign-up for both licenses and voter registration is often tied together.

“The current voter registration process at PennDOT is both harmful to election integrity and to members of the immigrant community seeking citizenship,” Mr. Schmidt said.

The data offers a boost to President Trump, who has claimed voters are tainted by noncitizens casting illegal ballots.

While Mr. Trump’s claims of millions of such votes have not been substantiated, Philadelphia’s data does show that fraudulent voting happens — contradicting the claims of voting rights activists who said it is so rare as to not be worth investigating.

Philadelphia’s numbers only look at noncitizens who later admitted they were wrongly on the rolls. There are likely to be other noncitizens who remain on the rolls without ever self-reporting.

Mr. Schmidt also predicted that if Pennsylvania were to study the problem statewide, they would expose a much higher level of bogus registration than the 220 noncitizens found in his city.

The problem has already cropped up in other states.

Studies earlier this year by the Public Interest Legal Foundation found thousands of illegal voters registered and casting ballots in both Virginia and New Jersey.

In each of those states, the PILF obtained records of persons who’d had their voter registration canceled because they admitted to being noncitizens, and then matched them up against voting records.

Logan Curchwell, a spokesman for the PILF, said the findings should spur changes to the 1993 National Voter Registration Act, commonly called Motor-Voter, which forced states to sign voters up while obtaining driver’s licenses.

“DMVs should never be in the business of offering voter registration to Green Card holders. The time is now to have a substantive discussion about rethinking Motor Voter,” Mr. Churchwell said.

He said it’s not just voter integrity that suffers. Those immigrants who later try to seek citizenship could have their applications delayed or even denied for voting illegally.

One woman was even deported last month for voting illegally.

Margarita Fitzpatrick claimed she was bamboozled into it by the clerk at the motor vehicle bureau in Illinois, who said it was “up to you” whether she should register to vote. She also checked “Yes” next to the box asking whether she was a citizen.

She voted in a couple of elections, then ran into trouble when she applied for citizenship in 2007, and admitted that she had in fact voted — illegally — before. An appeals court earlier this year ruled that Ms. Fitzpatrick spoke English well enough that there was no confusion and either knew, or should have known, that she wasn’t supposed to be voting.

The panel of judges in that case said the 1993 Motor-Voter law created a tricky situation since it forbids officials from saying anything that might discourage someone from registering. That left the employee to make the “unhelpful” statement that the decision to register was up to Ms. Fitzpatrick.