In his letter, Rio expressed serious concern over reports of students and people belonging to the northeast being attacked and threatened in certain parts of the country, including Mumbai, Pune, Hyderabad and Bangalore.
"We have also received reports that some people from Nagaland have been asked by their landlords to vacate their rented premises on the fear that people from the northeast are likely to be targeted by some groups of people who are aggrieved by the recent communal violence in lower parts of Assam," the letter, which was released to the media here, said.
"The situation had created an air of apprehension in the minds of the people of the northeast living in other parts of the country as well as among those here.
"It goes without saying that there are bound to be undesirable repercussions if the situation is not handled in an urgent and firm manner so as to reassure the safety of the people of northeast and to maintain communal harmony and peaceful situation in the country," Rio said in the letter.
He urged the Centre to take measures and also give directions to respective state governments to ensure that people of the northeast are not targeted in any manner.
Copies of the letter were sent to chief ministers of all northeastern states. Rio also sent separate missives to his counterparts in Maharashtra and Karnataka, CMO sources said.