New Delhi: Two more Air India pilots have failed preliminary drug tests ordered by the airline following the Phuket-Delhi flight incident that injured 17 people, sources said. The pilots have been de-rostered pending the results of confirmatory tests.

The Tata-owned airline had directed all its pilots to undergo drug screening as part of a new standard operating procedure after the captain of the Phuket-Delhi flight reportedly failed two preliminary urine tests conducted after the aircraft landed in Delhi. Marijuana was detected in the captain's system, according to sources, though the reported confirmatory result has not been officially confirmed by Air India.

More than 300 Air India pilots have undergone the screening so far. Sources said final laboratory results typically take 24 to 48 hours.

The airline's move follows the August 4 incident involving an Airbus A320neo operating from Phuket to Delhi. The aircraft suddenly lost around 91 metres (300 feet) of altitude, injuring 13 passengers and four crew members. It was carrying 137 passengers and eight crew and landed safely in Delhi.

Both pilots underwent routine post-flight screening for psychoactive substances. The Ministry of Civil Aviation said the captain's initial test required confirmatory testing and that both pilots had been removed from flying duties pending the inquiry.

A cabin crew member was also believed to have filed a complaint alleging that the captain had previously smoked cannabis.

However, there is currently no official finding linking the captain's reported drug-test result to the sudden loss of altitude. Investigators are examining the incident from multiple angles, including technical, operational, medical and human factors.