Agartala, The Union Health Ministry on Monday declared Tripura's Dhalai district headquarters Ambassa as a "red zone" - the state's first - after 14 Border Security Force (BSF) troopers there tested positive for Covid-19, a state Minister said.

Education and Law Minister Ratan Lal Nath said that that on Saturday and Sunday, 14 BSF troopers belonging to the 138 Battalion tested positive for coronavirus and are now undergoing treatment at the Govind Ballabh Pant Medical College and Hospital in Agartala, which is a dedicated Covid-19 hospital.

Six of Tripura's eight districts before Saturday were categorised as green zones while the remaining two districts were classified as orange zones.

Nath said Ambassa, 82 km north of Agartala, was declared a "Red Zone" as the 138 Battalion headquarters is situated there.

Dhalai District Magistrate Brahmneet Kaur has also declared three containment zones, including the BSF battalion headquarters, in the district.

"Around 331 people comprising 90 doctors and health workers and 241 BSF jawans were identified for directly or indirectly coming in close contacts with these 12 infected BSF troopers. Of the 331 identified people, swab samples of 179 people are being tested," Nath told the media.

He, however, added that despite the BSF battalion headquarters being in a locality and on a vital National Highway, the disease is yet to spread in the community.

A total of 16 Covid-19 cases so far found in Tripura and currently active cases are 14 as two people, including a woman, had discharged from the hospital after their recovery from the disease.

A week after the state was declared coronavirus free, two BSF troopers, including a head constable, tested positive for Covid-19 on Saturday.

A senior BSF officer told IANS that the head constable belonged to Assam and he has been suffering from some ailments after he returned to Tripura from his hometown in Sivasagar district on March 11.

"The ailing head constable and his attending colleague have tested positive for coronavirus at the Govind Ballabh Pant Medical College and Hospital in Agartala on Saturday," the officer, who did not want to be named, said.

With the recovery of Tripura's second patient, a 32-year-old Tripura State Rifles trooper and a resident of Uttar Pradesh, on April 25, the Tripura government had declared the northeastern state as coronavirus free. The state's first patient, a 45-year-old woman who tested positive for the virus on April 6 after she returned from Assam by train, has already recovered and was discharged on April 15.