Maziar Bahari, a Canadian journalist working for Newsweek, has been detained in Iran without charge. (CBC)

Newsweek magazine is demanding that a Canadian journalist detained without charge in Tehran be immediately released.

Maziar Bahari, 41, was taken by a group of men believed to be security officials from the apartment he shares with his mother in Tehran on Sunday morning, Newsweek foreign editor Nisid Hajari told CBC News.

Hajari said it is not clear who is holding Bahari.

Hajari said Bahari's mother told Newsweek the people who took her son "didn't clearly identify themselves and they didn't say when he would be back."

A laptop and several videotapes were also seized from the apartment by authorities, Hajari said.

At least 24 journalists and bloggers are also known to have been arrested in Iran since more than a week ago when Iranians began protesting the official results of the presidential election.

Bahari, who is originally from Tehran, but moved to Canada in 1988 and completed a degree at Concordia University in Montreal and keeps a home in Toronto, has been working in Iran for Newsweek for more than a decade, the publication said in a statement posted on its website.

'Deeply concerned'

"We are deeply concerned about Mr. Bahari's detention," Jon Meacham, editor for Newsweek, said in a statement.

"As a longtime Newsweek reporter, he has worked hard to be balanced in his coverage of Iran. We see no reason why he should be held by authorities," Meacham said. "We respectfully ask they release him as soon as possible."

Bahari has not been seen since he was taken into custody by authorities, Newsweek said, and there is no indication that he has been formally charged.

Bahari has worked as a journalist, documentary filmmaker and a playwright.

The magazine said that Bahari's detention is a violation of the free press in Iran.

"Newsweek asks that world government use whatever influence they have with the government in Tehran to make clear that his detention is unwarranted and unacceptable and demand Mr. Bahari's release," said Newsweek's statement.

Canadian government involved

The Canadian government has demanded to have access to Bahari, according to officials.

Hajari said the Canadian government has been informed of the situation and the Canadian Embassy in Tehran has been helpful in trying to locate the journalist.

On Monday, Prime Minister Stephen Harper issued a statement calling on the Iranian government to "release all political prisoners and journalists — including Canadians — who have been unjustly detained, to allow Iranian and foreign media to report freely on these historic events, and to conduct a full and transparent investigation into allegations of fraud in the presidential election."

Minister of State of Foreign Affairs Peter Kent said on Monday Canada is watching events unfold in Iran with great concern.

"There are serious questions about the election and the manner that it was carried out.… Canada certainly protests the sort of repressive violence that we have seen over the past several days," said Kent.

Peter Svatek, a Montreal resident who worked with Bahari on a documentary film about reporting in Iraq, said that his colleague was aware of the dangers of reporting from countries in the midst of political upheaval.

Svatek argued, however, that a line has been crossed. "Clearly the government in Iran is trying to send a message to the media by force and I think we should all stand up and oppose that."

The Iranian government has cracked down on foreign media — expelling and detaining some journalists and forbidding coverage of first-hand reporting, including images and witness accounts, from the streets of Tehran.

A BBC correspondent has been expelled and the Dubai-based network Al-Arabiya has had its rights in the country suspended.

With files from The Associated Press