Home Minister Rajnath Singh Monday said it is the top priority of Prime Minister Narendra Modi's government to ensure communal harmony in the country.In the wake of the suspected arson attack on a church in Delhi last week, the minister informed the Lok Sabha that a Special Investigation Team (SIT) has been constituted to probe the matter."On receiving the information about it (the attack on a Delhi church), I spoke with the lieutenant governor of Delhi, and told him to do a proper investigation. A SIT was immediately constituted to probe the matter," he said, while responding to a question raised by a member in the house.The home minister said that the investigation "has been made time bound as well".St. Sebastian's Church in Dilshad Garden was gutted in a fire Dec 1, leading to protests and sit-ins by Christians and their supporters asking for a detailed probe into the alleged arson.