Syed Munirul Islam was woken up by the ringing of his mobile phone around 5.45am. It was an unknown number. He reluctantly attended the call only to be offered herbal treatment for Covid-19 by a quack.

“The caller said he was calling from Guwahati and since I was ‘suffering’ from Covid-19, he would like to offer me herbal treatment. When I told him that I was not suffering from anything, he said my name and contact number figured in a Covid-19 positive list in Guwahati. I told him that I live in Delhi and perhaps my name figured in that list by mistake,” Islam, who hails from Latasil here but stays in Nizamuddin West in Delhi, 200 metres from the Markaz where the religious congregation took place, told The Telegraph over phone.

Islam has been going through the ordeal since Wednesday afternoon. “It all started with a call from a health official in Guwahati, followed by calls from the circle office, the deputy commissioner’s office, the police commissionerate in Guwahati and relatives and acquaintances since Wednesday afternoon. I was quite surprised when the officials asked me if I had attended a Tablighi Jamaat at Markaz in Nizamuddin West in Delhi. Then I was told that my phone number figured in a list of visitors to Nizamuddin between March 10 and 13.

“I had to explain to every caller that I have been staying as a tenant in the Nizamuddin West locality over the past two years and did not attend the congregation. One of the officers told me that the list contained a whole lot of names and phone numbers of people like me. He even told me that names and numbers of non-Muslim visitors to residences and offices in our locality also figured in the list,” Islam added.

Sources in the Kamrup (metro) deputy commissioner’s office said the list of numbers and names were provided by authorities in Delhi and all efforts were being made to trace people who had attended the congregation in Delhi which is considered to be the hotspot of coronavirus spreads in India. “It comprises many names of even passersby in the Nizamuddin locality on those three days and some have even taken offence when we called them up to enquire if they attended the Jamaat,” an official in the DC office told The Telegraph, wishing anonymity.

Sources said some non-Muslims, whose names figured in the list of 299 people that has gone viral on social media since Wednesday, have even received ostracisation threats on social media from their respective societies. When this correspondent tried to contact the listed non-Muslims, the calls went unanswered. Many numbers were found to be either switched off or invalid.

There are also numbers on the list which are supposed to belong to people from Assam but turned out to be those of either residents of Delhi or Uttar Pradesh. For instance, a call to the number of one Samir Paul, supposedly a resident of Guwahati, was attended by one Kamal in Paharganj area of Delhi who claimed it was his number.

A person from Jorhat whose name figures in the list said he had never visited Nizamuddin and was in Jorhat on the said days. “I have been receiving a whole lot of phone calls from the authorities besides my relatives and colleagues. I was at Jorhat at that time and I have never ever visited Nizamuddin area of Delhi in my life.”

An employee of a private telecom company did not rule out human errors in entry of KYC (know your customers) data by telecom operators or alleged issuing of multiple SIMs against one KYC document by private telecom operators.

Assam health minister Himanta Biswa Sarma had said on Friday that the government had traced 488 people, including some from outside the state, who had attended the Tablighi Jamaat and that measures were being taken for their well-being. He said about 15 people remain to be traced and hoped the government would do so soon.