Denis Dion, a spokesman for the electoral office, said there are certain cases that are more difficult to assess and the key point is to determine whether a person is committed to living in Quebec.
"It seems that some people trying to register don't always understand the rules," he said.
The comments come after a number of university students came forward saying they had been denied the right to vote.
Earlier Saturday, the controversy moved in a different direction when Montreal's Le Devoir cited an electoral officer who was concerned about the high number of anglophones and allophones trying to register to vote at a downtown Montreal riding.
The electoral officer told the newspaper some of the people didn't have proper documentation and called the situation "abnormal."
"It's as if (Montreal's) Trudeau International Airport was wide open and we distributed free visas to anyone who came through, without question," Mathieu Vandal, the president of local electoral office in Montreal's Sainte-Marie-Saint-Jacques, told Le Devoir.
Vandal resigned from his post on Friday.
With the spectre of another referendum looming over the election, there was speculation on social media of both an attempt at voter suppression or an orchestrated attempt to take down the PQ.
PQ leader Pauline Marois said Saturday she was concerned about the situation and called for the chief electoral office to look into it.
"It raises very serious questions," Marois said.
"This is a situation that worries me."
But Dion sought to downplay any problems on Saturday. He said nothing fraudulent is suspected, and officials are working to clarify to the voting requirements.
Voters must be a Canadian citizen and have lived in Quebec for six months, and have the intention of making Quebec their principal establishment, Dion said.
He said officials also take into account other evidence, such as proof of a bank account in a Quebec institution, a Quebec health insurance card or driver's licence, or a Quebec income tax return.
Meanwhile, a number of university students remain confused about their status.
One McGill student, Joey Broda, said he voted in the 2012 Quebec provincial election but was initially turned away this time when he tried to register.
Broda, a third-year engineering student and Winnipeg native, said he was finally able to register after going to a different office.
Part of the reason he wanted to register was because he was worried about another referendum, he said, but added: "It's also our democratic right."
Another McGill student, Dune Desormeaux, said Saturday he was turned away when he tried to register.
The 21-year-old, originally from British Columbia, said he thought he brought the necessary identification but was told he couldn't vote because he was a student.
Since moving to the province, Desormeaux said he has only returned to British Columbia for a few weeks a year.
"I had anticipated having no problems," he said.
"I brought the documents requested — my picture ID and a proof of address. And basically I was told, after a reasonably long discussion, that I would not be eligible to vote because I was not domiciled in Quebec as they said."
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