The 12 men and five youths accused of plotting to build bombs to set off in southern Ontario were supporters of al-Qaeda, law enforcement officials alleged Saturday.

"For various reasons, they appear to have become adherents of a violent ideology inspired by al-Qaeda," said Luc Portelance, Assistant Director of Operations for the Canadian Security Intelligence Service (CSIS).

Officers surrounded a police station in Pickering, east of Toronto, where the suspects were brought shortly after their arrests. (CBC)

"Any movement that has the ability to turn people against their fellow citizens is obviously something CSIS is very concerned about," said Portelance, although officials stressed there's no direct link between those charged and the militant group.

Raids involved 400 officers

Led by the RCMP's anti-terrorism task force, more than 400 police officers from across Ontario made the series of arrests Friday night and early Saturday morning.

Of the adults arrested, four are from Toronto, six are from nearby Mississauga, and two are from Kingston in eastern Ontario. The men range in age from 19 to 43.

Most of the suspects are Canadian citizens and all are residents, said police, who added that some are students, some are employed and some are unemployed.

The Mississauga suspects are Zakaria Amara, 20, Asad Ansari, 21, Shareef Abdelhaleen, 30, Qayyum Abdul Jamal, 43, Ahmad Mustafa Ghany, 21, and 19-year-old Saad Khalid.

Those from Toronto include Fahim Ahmad, 21, Jahmaal James, 23, Amin Mohamed Durrani, 19, and 25-year-old Steven Vikash Chand, alias Abdul Shakur.

The Kingston suspects were identified as 22-year-old Mohammed Dirie and 24-year-old Yasim Abdi Mohamed.

Rocco Galati, a lawyer for two of the Mississauga suspects, told the Canadian Press that Ahmad Mustafa Ghany is a health sciences graduate from McMaster University in Hamilton. He was born in Canada, the son of a medical doctor who emigrated from Trinidad and Tobago in 1955.

Shareef Abdelhaleen is an unmarried computer programmer of Egyptian descent, Galati said. He emigrated from Egypt at the age of 10 with his father who is now an engineer on contract with Atomic Energy of Canada, the lawyer said.

Lawyer gears up to fight charges

Another lawyer for some of the accused talked to reporters outside a courtroom in Brampton where the suspects were taken on Saturday. He said relatives of the accused are considering filing lawsuits.

"I think there are a lot of people here today who should not be involved in this," said Anser Farooq. "I think they cast their net far too wide."

The arrests mark the second time people have been detained under Canada's Anti-terrorism Act.

The first case involves Mohammad Momin Khawaja, an Ottawa-area man charged with participating in the activities of a British terrorist group and facilitating a terrorist activity. He is being held in an Ottawa detention centre, awaiting trial.