Security has been stepped up at Assumption Church in Kathmandu after the parish priest received a phone call from a Hindu extremist group threatening attacks against him and the church. A man claiming to be the leader of the Nepal Defense Army (NDA) telephoned Father Robin Rai on Friday, threatening further bomb attacks if the Catholic Church did not "help" the NDA. He ended the call without elaborating what he meant by "help". The group, which wants Nepal to return to being a Hindu state, has conducted several deadly attacks against Christian churches and Muslim targets over the past few years. In 2009 it launched a bomb attack on Assumption Church that killed three people, including a 14-year-old girl. It has also attmpted extortion from Christians and Muslims. “Within three or four seconds of the conversation, the person threatened to detonate bombs in our church if we refused to help his group,” Father Rai said. The man, who called himself Sangharsa - Fight - claimed the NDA was still active, despite the arrest of many of its key members since the 2009 church bombing. Its former leader, Ram Mainali, was arrested four months after the attack. Seven other members were picked up as recently as July 23 in raids during which police found explosives and weapons. Police were immediately informed about the threat. They have cautioned Christians to be extra vigilant and to tighten security at church-run institutions and services. Related reports: Bomb attempt targets Protestant churchChurch bomb-blast mastermind