The airports are currently run by the government, and labor unions representing airport workers angrily protested the privatization move Tuesday, fearing job cuts.

The GMR-Fraport consortium, a joint venture between India's GMR and Fraport AG that operates the Frankfurt airport, won the bid to modernise and operate the New Delhi airport, while a collaboration of India's GVK with Airports Company South Africa were successful in their bid for the Bombay airport, Civil Aviation Minister Praful

Patel told reporters late Tuesday.

The federal Cabinet will formally approve the names of the two bidders on Wednesday, Patel said.

The government has launched a sweeping program to modernise its aging airports, currently struggling to cope with booming air traffic brought about by India's rapid economic growth.

Between them, the New Delhi and Bombay airports handle almost 65 percent of India's international traffic - about 19 million passengers a year. Both airports have long been criticised for their inefficiency and lack of comfort.

The Airport Association of India Employees Union said it would launch strikes at all Indian airports as soon as the winners are formally announced.

"Whether you call it a strike or boycott, it doesn't matter. We have informed the minister. All the unions across the country are prepared for it," MK Ghoshal, the union convener, was quoted as saying by Press Trust of India.

Employees fear job cuts after the privatisation. Under the contracts, however, the new airport operators must retain the current employees of state-run Airports Authority of India for at least three years.