NEW DELHI: Flyers at Mumbai Airport will have to shell out more from April this year as the tariff regulator AERA has allowed MIAL to charge an additional levy of Rs 20 for domestic flying and Rs 120 for international travel as development fee to fund a metro rail project.The Airports Economic Regulatory Authority (AERA), in an order today, said the additional levy shall be merged with the existing airport project development fee.Mumbai International Airport Limited (MIAL), the private airport operator, currently levies a development fee of Rs 600 from an international passenger and Rs 100 from a domestic passenger. Development fee is charged only from departing passengers."The Authority hereby determine (additional) development fee at Rs 20 per domestic embarking passenger and Rs 120 for international embarking passenger for funding the metro connectivity project for Chhatrapati Shivaji International Airport, Mumbai," the airport tariff regulator said.The additional levy would be applicable from April 1, 2016 and remain in force till March 31, 2021, it said.MIAL had last year sought AERA's permission to charge additional development fee, to fund the metro rail project.Mumbai Metro Rail Corporation (MMRC), the project implementing company for all metro rail corridors across the western metropolis, is to construct a 32.5-km underground line, connecting Colaba in South Mumbai to SEEPZ in western Andheri suburb. MMRC , on its part, has sought funding contribution from MIAL.