Police are investigating the details of a letter received by the international airport here threatening to plant bomb if the demands of teaching community was not met by the Centre and State Governments.

The letter received by Airport Authorities last evening sought pay parity for teachers with Central Government staff and teachers and also demanded that new pension scheme be withdrawn.

According to police, the letter, sent from Anna Nagar First Street, had names of Bhaskaran, Gouri and Chandrasekharan and a mobile number, which however was switched off. It threatened to plant bomb to cause explosion if the demands were not met.

Security has been beefed up in and around the airport here. Vehicle checks have been intensified and passengers are screened before allowing them on the premises, police said.

Last week, a similar letter was received by the Madurai airport.