Toronto police incinerated some potentially explosive material on Thursday, found inside the house of a G20 activist who is currently on trial.

A small pile of the material smoked and burned on a rocky outcrop of the Leslie Spit, swelling into a massive bonfire of sharp orange flames before burning itself out Thursday afternoon.

Forensic investigators and bomb disposal crews had gathered on the Leslie Spit Thursday morning after the materials were transported to the isolated location overnight.

The original plan had appeared to be destroying the material in a controlled explosion. But after a morning of preparation, bomb disposal robots probed the packaged material and brought a sample back for investigators to examine.

Toronto police said they determined the most appropriate course of action to be a controlled burning of the substance, rather than a full explosion. The fire lasted about five minutes leaving a pile of char and ash in its place.

The burn came nearly one full day after police seized the suspicious material from outside the house of Byron Sonne, a G20 activist who is currently on trial for four counts of possession of explosives.

Police units -- including the bomb disposal unit, OPP tactical and hazmat teams -- arrived at Sonne's home at 58 Elderwood Dr. near Bathurst and Eglinton Avenue around 10:15 a.m. Wednesday.

Police Det. Tam Bui said the execution of a search warrant at Sonne's house was motivated by evidence presented during his court case on Monday.

Because the court case is active, Toronto police could not say what they were looking for in the house.

But police found something in a container in the backyard with additional containers inside it.

Police Const. Wendy Drummond said the discovery of possibility of dangerous materials was a "concern" for bomb experts.

Sonne has been in custody since June 2009 when he was charged, and this new investigation came after the final day of arguments in Sonne's court case on Monday.

Sonne was originally arrested on a TTC bus he was riding downtown after allegedly getting caught hacking into secure G20 websites.

His home and cottage were searched in 2009 during the G20 summit.

Sonne, who is a computer programmer and a hobby chemist, admitted to having chemicals at his home that could be combined to make explosives, but said he never combined or "weaponized" them.

His defence team argued that Sonne made poor decisions in trying to expose the exorbitant $1-billion G20 security system by showing how easy it was to hack. He was also trying to prove that one could access the materials to make explosives without getting caught, his defence team said.

Sonne faces up to 10 years in jail if convicted.

Justice Nancy Spies will give a decision on May 23.

With files from CTV Toronto's John Musselman