Another member of the "Toronto 18," a group that plotted to blow up a number of prominent buildings in the city, has pleaded guilty to a terrorism charge.

Ali Mohamed Dirie, 26, pleaded guilty on Monday to one count of participating in the activities of a terrorist group, said the Public Prosecution Service of Canada.

The group had planned to detonate bombs outside the Toronto Stock Exchange and the headquarters of CSIS, Canada's spy agency.

Dirie is the second adult to admit to being part of the plot.

His plea comes four months after Saad Khalid pleaded guilty to one count of participating in a militant plot with the intention of causing an explosion. He was sentenced earlier in September to 14 years in prison, but was credited with seven years for time already served.

In all, 17 men and youths were arrested in the Toronto area in June 2006 and detained following an investigation by CSIS. An 18th person was arrested in August of that year.

Khalid is among 17 who were charged with several offences. The charges were later stayed or dropped against some of the accused.

Nishanthan Yogakrishnan, a minor at the time of his arrest, was tried under youth justice laws and convicted in September 2008 of conspiring to bomb several targets. He was the first person convicted under Canada's terrorism laws.

The presiding judge found he had continued his activity with the group past his 18th birthday, so he was sentenced as an adult in May 2009, getting a 2½ year prison term. The judge then freed him, granting him credit for time already spent in custody.