NEW DELHI, Sept. 20 (Xinhua) -- As many as 30 passengers have been injured after cabin pressure dropped in a passenger plane soon after it took off from India's financial capital Mumbai Thursday, aviation officials said.

The Boeing 737 aircraft belonged to private carrier Jet Airways and it was on its way to the western Indian state of Rajasthan's capital Jaipur with 166 passengers on board.

"The 9W 697 Mumbai-Jaipur flight was turned back to Mumbai after take-off as, during the climb, crew forgot to select switch to maintain cabin pressure. This resulted in the oxygen masks dropping," Lalit Gupta of Directorate General of Civil Aviation, told the media.

"Thirty out of 166 passengers experienced nose and ear bleeding, some also complained of headache," he added.

Jet Airways has also regretted the incident and said it has taken the flight crew off duty, pending an investigation.

India's Civil Aviation Ministry has ordered a probe by the Aircraft Accident Investigation Bureau, officials said. "It will be probed if it was a human error or technical glitch," an official said.