India's aviation regulator has issued a warning notice to airline SpiceJet after a review of recent incidents — including an aircraft's emergency landing at Karachi airport — showed "poor internal safety oversight and inadequate maintenance actions" by the airline.

The airliner carrying 132 passengers and 12 crew members from Delhi had on Tuesday made an unexpected landing at Jinnah International Airport Karachi after reporting some fault and seeking permission from authorities.

India's Directorate General of Civil Aviation (DGCA) said that a review of several incidents involving SpiceJet's planes since April 1 showed that "the aircraft either turned back to its originating station or continued landing to the destination with degraded safety margins".

On July 5 alone SpiceJet reported two mid-air problems.

In one incident, SpiceJet was forced to divert its Boeing 737 plane to Karachi due to an indicator light malfunctioning. Both planes landed safely.

In the second case, the side windshield outer pane of its Bombardier Q400 aircraft cracked mid-flight. In the second case,

"The review transpires that poor internal safety oversight and inadequate maintenance actions has resulted in degradation of the safety margins," the DGCA said in its letter in which it has given the airline three weeks to respond.

"From the above it may be deducted that SpiceJet has failed to establish a safe, efficient and reliable air service," the watchdog said in its letter dated July 5 which was made public by India's civil aviation ministry on Twitter on Wednesday.

SpiceJet, whose shares fell to their lowest since March 2020 in morning trade, said it is committed to ensuring a safe operation for its passengers and crew.

"We have been regularly audited by DGCA. All our aircraft were audited a month ago by the regulator and found to be safe," the company said, adding that all its flights are conducted in compliance with aviation regulations.

In September, during a financial review of the airline, the DGCA found that SpiceJet's suppliers were not being paid regularly leading to a shortage of spares.

The regulator did not name the suppliers and the company did not provide direct comment on the issue.

"Passenger safety is paramount," India's civil aviation minister, Jyotiraditya Scindia, said on Twitter.

"Even the smallest error hindering safety will be thoroughly investigated and course-corrected," he said.

Shares of the Indian budget carrier have fallen 43.4 per cent so far this year, compared to a 17.6 per cent fall in rival Interglobe Aviation.