Tahawwur Rana, a Canadian citizen, has been charged with helping to plot a terrorist attack in Denmark. Tahawwur Rana, a Canadian citizen, has been charged with helping to plot a terrorist attack in Denmark. (Verna Sadock/Associated Press)

A Canadian citizen accused of helping plot a terrorist attack in Denmark has been refused bail by a judge in Chicago.

Tahawwur Rana, who emigrated to Canada from Pakistan in 1997, will remain behind bars after U.S. Magistrate Judge Nan Nolan ruled that he posed a flight risk.

Nolan said she wasn't convinced that Rana wasn't a significant flight risk given his strong ties to Canada and his Canadian citizenship.

Rana, now a Chicago-based businessman, is one of two men nabbed by the FBI in October and charged with plotting a terrorist attack.

The bail decision comes a day after U.S. federal prosecutors presented fresh allegations against Rana.

They said he knew in advance about last year's terrorist attacks in Mumbai, India, and sent along congratulations to its perpetrators for their excellent planning.

"Rana was told of the attacks before they happened and offered compliments and congratulations to those who carried them out afterwards," assistant U.S. Attorney Daniel Collins wrote in the court filing Monday.

"It is clear from the conversation and extrinsic corroboration that Rana was told just days before the Mumbai attacks that the attacks were about to happen," prosecutors wrote.

Rana owns an immigration consulting firm in Toronto and a home in Ottawa, where his brother lives. He has insisted he had no knowledge of the Mumbai attacks in November 2008. A total of 166 people, including two Canadians, were killed.

His co-accused, David Coleman Headley, is also charged in the Mumbai attacks.

Two weeks ago, U.S. Magistrate Judge Nan Nolan said she wanted to take time to review the prosecution evidence against Rana, including a five-hour video of his statement to the FBI following his arrest.

Patrick Blegen, Rana's lawyer, produced three witnesses at that hearing, including Rana's brother-in-law, who described his "honest and trustworthy character."

The bail hearing for Rana's alleged accomplice has been indefinitely postponed. Rana has been friends with Headley since they were children in Pakistan.

Rana is charged with providing material support to terrorists.