The 34th Kalchakra puja was initiated on Monday by Tibetan spiritual leader Dalai Lama in Bihar amid tight security arrangements, officials said."The 10-day-long Kalchakra puja began with a sermon by the Dalai Lama in Bodh Gaya," a district official said.After his sermon, the Dalai Lama conducted a special prayer for world peace and other rituals followed by devotees.Kalchakra puja is considered to be the most important ritual of the Mahayana sect of Buddhism.Gaya district magistrate Ravi Kumar said security in Bodh Gaya had been tightened in view of the presence of the Dalai Lama and the 17th Karmapa."Foolproof security has been arranged for the Dalai Lama at Bodh Gaya as he faces a serious threat to his life," he said.Nearly two lakh devotees from all over the world are likely to attend the 10-day-long puja to hear a discourse by the Dalai Lama. Thousands of Tibetans have already arrived here.The spiritual leader arrived in Patna on Wednesday and visited Budha Smriti Park along with Bihar Chief Minister Nitish Kumar and participated in a tree-plantation drive.