Agartala,  Even as the BSF is conducting a probe to trace the source of novel coronavirus infection among 24 personnel and three family members of a jawan in Tripura, authorities identified 331 persons who came in contact with infected persons, official sources said on Tuesday.

The swab samples of 179 of the identified contacts have been sent for testing.

"We are conducting an inquiry to know about the primary and secondary sources of infection in these BSF jawans and their family members," the top BSF officer of Tripura frontier told IANS on the condition of anonymity.

He said that the BSF authorities in cooperation with the Tripura government have taken all precautionary and other steps at the 138 Battalion headquarters at Ambassa, 82 km north of Agartala.

According to Tripura's health officials, 24 BSF personnel belonging to the 138 Battalion, wife of a jawan and their two children had tested corona positive on Saturday, Sunday and Monday.

Education and Law Minister Ratan Lal Nath said: "As many as 331 people, comprising 90 doctors and health workers and 241 BSF jawans, were identified for directly or indirectly coming in contact with infected BSF troopers. Of the 331 identified people, swab samples of 179 people are being tested," Nath told the media.

"Despite the BSF battalion headquarters situated in a locality on a vital National Highway, the disease is yet to spread in the community," the Minister said.

Nath said that the Health Ministry on Monday had declared Tripura's Dhalai district headquarters Ambassa as "Red Zone" after many BSF troopers tested positive.

He said that all the 27 infected persons are now admitted at the Govind Ballabh Pant Medical College and Hospital in Agartala, a dedicated Covid-19 hospital.

Six of the eight districts of Tripura, before Saturday, were categorised as green zones and two districts as orange zones.

Dhalai District Magistrate Brahmneet Kaur has declared three containment zones -- the BSF battalion headquarters, their administrative base camp at Gandachara and Karina Border Outpost (BoP).

As many as 29 positive cases have so far been reported in Tripura, with 27 active cases. A woman and a Tripura State Rifles (TSR) jawan were cured and discharged from hospitals.

A week after the state was declared novel coronavirus free on April 25, two BSF jawans -- including a Head Constable -- tested positive on Saturday at the 138 Battalion.

According to BSF officials, the Head Constable was the first to be infected. Belonging to Assam, he has been suffering from some ailments after he returned to Tripura from his hometown in Sivasagar district on March 11.

Tripura's first coronavirus patient, a 45-year-old woman, who tested positive on April 6 after her return from Assam by train, has already recovered and was discharged on April 15.