AGARTALA, June 16: Authorities in the northeastern region have stepped up precautionary measures against the spread of swine flu, besides banning import of pigs and pork products from adjoining countries, officials said Tuesday. A health official said no case of influenza A(H1N1) infection had been reported in Mizoram, Manipur, Meghalaya and Tripura. However, these states have banned import of pigs and pork products. The northeastern states share unfenced borders with Myanmar, Bangladesh, Bhutan and China.