One such notice served is in the name of Banne Khan, who died six years ago at the age of 94.

In large-scale violence that engulfed many parts of Uttar Pradesh during protests against the citizenship law two weeks ago, 21 people died, many others including police personnel were injured and there was large-scale destruction of government and private property, also allegedly by the police personnel who were accused of clamping down in an arbitrary manner.

In western Uttar Pradesh's Firozabad, where four people died in clashes on December 20, about 35 cases were registered over the violence, 29 people named in them and 14 people were arrested and jailed by Firozabad Police.

After the violence subsided, the local police sent out notices to at least 200 people asking them to prove they would not be a threat to peace in the area. The move comes after Chief Minister Yogi Adityanath's promise of action on protests - "We will take badla (revenge) on them," he had said last month.

One such notice served is in the name of Banne Khan, who died six years ago at the age of 94.

Two other men in their 90s - 93-year-old Fasahat Meer Khan who has been bedridden for months and 90-year-old Sufi Ansar Hussain, who is suffering from pneumonia and has just returned from a Delhi hospital after his treatment, have also received similar notices.

Mr Khan is the founder of a college in Firozabad while Mr Husaain has been a caretaker at a local mosque for about six decades. Both men are members of their local peace committees that have distinguished members of civil society and regularly coordinates with the police for maintaining peace in any area.

In notices issued to both men, they were asked to appear before a government magistrate and apply for bail after submitting a bond of Rs 10 lakh.

"I was at Delhi's Gangaram Hospital on December 25 and returned only yesterday. I have no why they did this. I have spent all my life to ensure peace in the city. I don't understand why this was done to me at the age of 90. There was in Urs on December 20 and I had invited the authorities," Ansar Hussain said.

The Uttar Pradesh government says this was an error and will be rectified.

"There was a lot of pressure on us to maintain peace and these were interim measures taken based on reports from various police stations," Firozabad City Magistrate Kunwar Pankaj Singh was quoted as saying by news agency ANI. "No action will be taken against any elderly people," he added.

Protests against the new citizenship law were held in several parts of Uttar Pradesh, including Firozabad. Chief Minister Yogi Adityanath had warned of a "crackdown" on the protesters and the government ordered that those found responsible for damaging public property during the protests would have to pay for it.

The Citizenship (Amendment) Act for the first time makes religion the test of citizenship in India. The government says it will help minorities from three Muslim-dominated countries to get citizenship if they fled to India because of religious persecution. Critics say it is designed to discriminate against Muslims and violates the secular principles of the constitution.