A significant number of passengers who disembarked from SpiceJet's Hyderabad-Delhi flight on Saturday night walked on the airport's tarmac as the airline could not provide a bus for around 45 minutes to take them to the terminal, sources said.

Aviation regulator DGCA is investigating the incident, sources told PTI on Sunday.

Spicejet, however, said there was a brief delay in the arrival of coaches, and once the buses came, all the passengers, including those who had started walking, travelled on them from the tarmac to the terminal building.

"Despite repeated requests from our staff, a few passengers started walking towards the terminal. They had barely walked a few metres when the coaches arrived. All passengers, including those who had started walking, travelled on the coaches to the terminal building

Passengers are not allowed to walk on the Delhi airport's tarmac area as it is a security risk. There is a demarcated path on the tarmac for vehicles only.

Therefore, the airlines use buses to take passengers from terminal to aircraft or vice versa using the demarcated path.

Currently, SpiceJet is operating not more than 50 per cent of its flights as per the orders of the Directorate General of Civil Aviation (DGCA).

The regulator had in July imposed the curb on the airline's flights for a period of eight weeks as its planes were involved in at least eight incidents of technical malfunction in the June 19-July 5 period.

SpiceJet's Hyderabad-Delhi flight -- which had 186 passengers on board -- landed at its destination at around 11.24 PM on Saturday, sources said.

One bus came immediately and took a section of the passengers to the terminal 3, they said.

The rest of the passengers waited for about 45 minutes, and as they didn't see any bus coming for them, they started walking towards the terminal which was about 1.5 km away, they noted.

After these passengers walked for around 11 minutes on tarmac, a bus came at around 12.20 PM to take them to the terminal, they said.

When asked about this incident, SpiceJet said in a statement: "The information that passengers of SpiceJet flight Hyderabad-Delhi on 6th August were forced to walk towards the terminal on foot is wrong and is denied.

"There was a brief delay in the arrival of coaches to ferry the passengers from the tarmac to the terminal building."

"Despite repeated requests from our staff, a few passengers started walking towards the terminal. They had barely walked a few metres when the coaches arrived. All passengers, including those who had started walking, travelled on the coaches to the terminal building," the airline mentioned.