TORONTO (Reuters) Zakaria Amara, considered the ringleader of the Toronto 18 extremist Muslim group that planned al Qaeda-style bombings of Toronto landmarks in 2006, was given a life sentence on Monday, the stiffest penalty yet imposed under Canadian anti-terrorism laws. The sentence, handed down in a Toronto-area court, is the fourth custodial term handed out in the sprawling case, and follows a 12-year sentence given earlier in the day to admitted co-conspirator Saad Gaya. Amara, 24, pleaded guilty in October to charges of planning explosions likely to cause serious bodily harm or death and of participating in the activities of a terrorist group. His sentence includes a life term for the first charge, and a nine-year term for the second, the federal prosecutors office said in a statement. Given credit for time already served, he will be eligible for parole in just over six years. Prosecutors say Amara was the leader of a group that had planned to detonate truck bombs near targets such as the Toronto Stock Exchange, the CN Tower, an Ontario military base and the Toronto offices of the national spy agency. The aim was to force Canada to withdraw troops from Afghanistan. In reading the decision, Ontario Superior Court Bruce Durno said the crime envisioned by Amara would have been one of the most horrific in Canadian history, media reported. Earlier in his sentencing hearing, Amara renounced his extremist views and said his interpretation of Islam was naive and gullible. Most members of the group dubbed the Toronto 18 by the news media were arrested in June 2006 after trying to buy what they thought was three tonnes of ammonium nitrate the bomb-making ingredient used in the Oklahoma City bombing from undercover police officers. Police had in fact been monitoring the group for months, aided by two paid undercover informants. Coming in the wake of the 2005 London Underground bombings, the arrests sparked fears that home-grown Muslim terror cells could be plotting similar attacks within Canada. It also placed the spotlight on Canadas border security, which has been long criticized by the United States, and came under additional scrutiny after September 11, though none of the 9/11 terrorists entered the United States from Canada. The massive prosecution has also been seen as a test of Canadas Anti-Terrorism Act, passed in the wake of the September 11 attacks on the United States. Since the Toronto 18 arrests, charges against seven members of the group have been dropped, while trials for six none of whom are facing charges on the explosives, the most serious have yet to begin. Gaya, 22, who was also sentenced on Monday, pleaded guilty in September to the explosives charge. He was given credit for 7-1/2 years due to pre-trial time served since the arrests four years ago. Saad Khalid, who along with Gaya was caught unloading what they though were bags of fertilizer from a truck, was sentenced to 14 years in September, and given credit for seven years. Mohamed Dirie was sentenced to seven years in October, and given credit for five years, while one of five youths charged in the case, who cannot be named due to their age at the time of the arrest, pleaded guilty two years ago and was sentenced to time served.