Guwahati/Agartala, With more positive coronavirus cases getting reported from the region, the total number cases in the northeast went up to 20 on Thursday, including 16 in Assam, officials said.

Of the 20 positive cases, 18 took part in the Tablighi Jamaat congregation at Nizamuddin Markaz in Delhi while a Manipuri girl and a Mizoram man had tested positive last month after they returned from the UK and the Netherlands, respectively.

According to Assam Health Minister Himanta Biswa Sarma, three attendees of the Tablighi event held last month from the state's Goalpara district have tested positive for coronavirus, taking the state's tally to 16.

Manipur Chief Minister N. Biren Singh said in a tweet that one more positive case has been detected on Thursday, taking the state's tally to two.

According to an official release by Manipur's Directorate of Information and Public Relations, a 65-year-old man from Lilong has tested positive and is undergoing treatment now at the Regional Institute of Medical Science in Imphal.

Arunachal Pradesh Chief Minister Pema Khandu said in a tweet that a 31-year-old non-Arunachalee man, who participated in the Tablighi Jamaat congregation, has tested positive for coronavirua, becoming the first Covid-19 patient in the state.

"At present, he is asymptomatic and has been kept in isolation. His condition is stable," the Chief Minister said.

Sarma had earlier said that the Centre has communicated to the state that 556 people from Assam had attended the Tablighi meet.

"Of the 556 people, 230 have been identified while 68 have not yet returned. Around 193 people are in hiding. Of the 230 people, swab samples of 196 are being tested," Sarma said. He also said that efforts are on to trace the other unidentified persons.

The Health Minister said that four persons from Assam, who attended the congregation but remained in Delhi, have tested positive for Covid-19.

"I am very angry and frustrated as despite our repeated appeals, none of the participants reported to the authority. Why are you hiding your cases," Sarma told a national television channel.

Assam had reported its first Covid-19 case on Tuesday when a 52-year-old man's swab sample tested positive. According to the health officials, all the patients in Assam are aged between 19 and 70 years and are undergoing treatment at different hospitals in in the state.

According to the ministers and officials of northeastern states, over 500 people from several of these states, mostly from Assam, had either attended or were in vicinity of the Tablighi congregation, forcing all seven states to launch an all-out search to identify and test these persons.

The attendees' family members and the people they came in close contact with are also being examined or sent to quarantine.

In Tripura, the nodal officer for Covid-19, Deep Debbarma, told IANS that swab samples of 33 people comprising those from the state who attended the Tablighi meet or went to the Nizamuddin area, including their family members, have tested negative.

In Imphal, Manipur Director General of Police L.M. Khaute asked the attendees from the state or those who even stayed in vicinity of the meeting venue or passed near it should get themselves tested at the nearest government hospital, warning of legal action otherwise.

Seven people from Meghalaya attended the Tablighi religious congregation, the Shillong Markaz informed the police, saying they have not yet returned.

"It is confirmed that five are currently in Delhi and two are in Lucknow. The same has been conveyed to the police of Delhi and Uttar Pradesh," Meghalaya Chief Minister Conrad K. Sangma said in a tweet.

In Nagaland, media reports said that some persons from Nagaland had either attended or were in the vicinity of the congregation venue in Delhi. The officials of the Health and Family Welfare Department along with the district administrations and the police have begun the process of tracking them down.

Three northeastern states -- Nagaland, Meghalaya and Tripura -- are yet to report any positive coronavirus case.