SINGAPORE (BLOOMBERG) - India is investigating why more than half of flights by IndiGo, Asia's biggest budget airline by market value, were delayed last Saturday (July 2), said the head of the nation's Directorate General of Civil Aviation.

Many employees reported sick so that they could attend interviews at Air India, which is on a hiring spree under new owners Tata Group, local media reported.

The delays come as airlines and airports globally struggle to keep up with a sudden surge in demand as pandemic restrictions are lifted.

Formerly state-run Air India, once known for its premium service and advertisements featuring Bollywood stars, is trying to rejuvenate itself under new owners. It is preparing to order as many as 300 narrow-body jets, on top of a deal for larger transcontinental aircraft.

Last week, the carrier warned it could drop a former sister company as its preferred ground-handling provider as poor service impacts operations at some airports.

IndiGo, which has risen from an ambitious venture of a little-known travel firm to control more than half of the world's fastest-growing aviation market, prides itself on punctuality, with a popular tagline saying "On time is a wonderful thing".

While the airline offers no-frills flights, it has been able to win customers with cheap, on-time services, with the help of efficient staff that have ensured planes do not stay on the ground for long.