Airport operators, including state-run Airports Authority of India which have invested thousands of crores to upgrade infrastructure, have started lobbying with the government to allow more foreign carriers to operate from their facilities. The move is expected to help the airport firms improve their revenue and recover investment.While GMR Hyderabad International Airport is in favour of allowing Tiger Airways to operate flights to the IT city, the AAI wants the Malaysian no-frill carrier, Air Asia, to start services to Kolkata. The AAI is in the process of investing nearly Rs 2,500 crore to upgrade the Kolkata airport. The public sector agency has earmarked a budget of about Rs 12,700 crore during the current Five Year Plan to upgrade the airport facilities, which include non-metro airports such as Dehradun, Ahmedabad and Patna.The airport operators’ demand is valid and hence under consideration. Increased flights would help airport operators recover the cost, a civil aviation ministry official said. He, however, said a decision would not be taken in a hurry.Led by private airport operators, Delhi International Airport and Mumbai International Airport , the airport sector has seen an investment of over Rs 40,000 crore in the last few years. More aircraft movement would add up to their aeronautical and non-aeronautical revenues.International traffic to and from India has nearly doubled to 29.6 million in the last five years on the back of strong economy.