All new patients returned to the state from Chennai on May 22 by a Shramik Special train.
The train brought back 1,328 residents of the state, who were stranded in different parts of Tamil Nadu due to the lockdown imposed to contain the spread of the virus.
"Nine more tested COVID-19 positive. All returnees from Chennai. Six are from Dimapur and three are from Tuensang district," the minister said in a tweet.
Five persons were detected with the infection on Wednesday.
Meanwhile, one Chennai-returnee was released from a quarantine centre in Kohima on Tuesday before his test results arrived, an official said.
He was found positive for COVID-19 on Wednesday, the minister said.
The person reached Tuensang district along with 150 others who came from the southern state.
"Contact tracing are in process and the patient is being taken care by Tuensang medical team," Phom said on Wednesday.
The Nagaland government has not counted a person from the state who tested positive for coronavirus on April 13 in Assam after a private hospital referred him to a government facility in Assam's Guwahati. He later recovered from the disease. NBS BDC BDC