The preliminary hearing has begun for 14 Ontario men accused of participating in an alleged terror plot to bomb locations in Toronto and Ottawa.

The suspects appeared in a Brampton, Ont. courtroom on Monday for the proceeding. The hearing is expected to last all summer, while any trial could still be years away.

"I think, realistically, we won't see a trial until 18 months from now, and that's optimistic," said lawyer Rocco Galati.

Another counsellor said the trial could last between three and five years, which would make it one the longest criminal trials in Canadian history.

A publication ban forbids the reporting of evidence heard during the preliminary hearing.

Security was tight in the courtroom, which was filled with family and friends of the accused, CTV's John Musselman reported.

Lawyers have complained about the alleged treatment of the suspects, most of whom are being held at the Maplehurst detention centre in Milton.

Seventeen suspects were arrested during sweeping raids last June in the Greater Toronto Area. An 18th individual was arrested a couple of months later.

One 16-year-old suspect was freed in February after charges against him were stayed by the Crown. A few others have been released on bail.

Police claim the group of predominantly young, Canadian-born Muslims planned to bomb Toronto and other southern Ontario targets.

The suspects are also accused of participating in terrorist training in central Ontario and planning to behead Members of Parliament.

With a report from CTV's John Musselman