The vigil was tightened on the instructions of the Central government, he said.
"Three companies of Assam Rifles included personnel from its battalion headquarters at Aizawl, Serchhip and Lunglei," he said.
The other five companies had personnel from Assam, Manipur and Nagaland, he added.
The official, however, expressed doubts that Rohingyas would enter Mizoram as the Rakhine state in Myanmar, where they were concentrated, was too far from the border and the language, religion and culture of the Mizo people were different from that of theirs.
The Indian government has decided to deport Rohingya refugees from India.
Members of the community have been fleeing from Myanmar to neighbouring countries in recent times after facing violence and persecution.