Canadian foreign ministry officials summoned Algeria's ambassador late on Monday to make the request directly.
Around 80 people died when Algerian troops attacked the plant and ended the hostage-taking on Sunday. Algerian Prime Minister Abdelmalek Sellal said on Monday that a Canadian gunman, identified only as "Chedad", had coordinated the four-day siege.
"Here in Ottawa and in Algiers, Canadian diplomats are requesting access to the information the Algerians are using to identify any hostage taker as 'Canadian'," the government official said in an email sent to Reuters.
"Canada summoned the Algerian ambassador to Canada to make that point directly," he added.
One U.S. counter-terrorism expert told Reuters on Monday he had heard the hostage-takers included at least two Canadian nationals, one of whom may have spoke English with a North American accent.
Ottawa says it has not yet received any information from Algiers about supposed involvement by Canadian citizens in the hostage-taking.
No one was immediately available for comment at the Algerian embassy.
Canada's spy agency and various police forces have expressed concern for years about militant citizens leaving the country to train with radical groups.
Two European security sources said on Tuesday they were skeptical of Algeria's claim that a Canadian militant had been in command of the hostage-takers.
In the past, small numbers of Canadians or Canadian immigrants from North African and South Asian backgrounds have been linked to operations or factions connected to al Qaeda or its affiliates.
Canadians suspected of ties to North African Islamic militants historically have come from French-speaking Quebec, rather than from English-speaking Canadian provinces.
(Additional reporting by Mark Hosenball; Editing by Peter Galloway)