Three people were killed in the blast at the Nirankari Bhavan near Amritsar's Rajasansi.
Punjab Chief Minister Amarinder Singh on Monday announced a reward of Rs 50 lakh for anybody providing information on those involved in the Amritsar grenade blast that left three persons dead, officials said.
Information can be provided on the Punjab Police helpline - 181, officials said, adding the identity of the informer will be kept a secret.
The chief minister will visit Amritsar later in the day, officials said. A team of the National Investigation Agency visited the blast site Sunday night along with their investigators and explosive experts.They also held discussions with the top officials of the Punjab Police.
Three persons, including a preacher, were killed and over 20 injured when two-motorcycle borne men threw grenade on a religious congregation on the city outskirts here on Sunday, an incident which the police are treating as a "terrorist act".
The incident took place inside the Nirankari Bhavan's prayer hall at Adliwal village near Amritsar's Rajasansi, police said.
A religious congregation of the Nirankari followers was being conducted inside the Bhavan at the time of the incident.
The Sant Nirankari Mission is a spiritual organisation and the Bhavan here lies close to the international airport and the Indo-Pak border.