SpiceJet said its flight heading to Jabalpur returned to Delhi on Saturday after crew members observed smoke in the cabin at around 5,000-feet altitude.

There was oil leakage in one of the engines of the Q400 aircraft and that is likely the reason for smoke in the plane, officials of aviation regulator DGCA said after preliminary investigation.

This is fifth such incident on SpiceJet aircraft in two weeks. The Directorate General of Civil Aviation (DGCA) is investigating all the five incidents.

On June 19, an engine on SpiceJet's Delhi-bound aircraft carrying 185 passengers caught fire soon after taking off from the Patna airport and the plane made an emergency landing minutes later. The engine malfunctioned because of a bird hit.

In another incident on June 19, a flight for Jabalpur had to return to Delhi due to cabin pressurisation issues.

Fuselage door warnings lit up on two separate planes while taking off on June 24 and June 25, forcing the them to abandon their journeys and return.

"On July 2, 2022, SpiceJet Q400 aircraft was operating SG-2962 (Delhi-Jabalpur)," the airline's spokesperson said in a statement.

At 5,000 feet, the crew noticed smoke in the cabin, the spokesperson noted.

"The pilots decided to return back to Delhi. The aircraft landed safely at Delhi and passengers were safely disembarked," the spokesperson said.

An alternate flight was immediately arranged for affected passengers and it has already reached Jabalpur, the spokesperson added.

It is not clear how many passengers were travelling on Delhi-Jabalpur flight in which the smoke incident took place.