Several Air India flights from Mumbai were delayed on Thursday morning after a group of contractual workers went on a strike, leaving passengers helpless and fuming. Media reports suggest that the state-run airline had to call staff from home to help with the check-in process. The contractual ground staff of Air India Air Transport Services Limited (AIATSL), a wholly-owned subsidiary of Air India, are on a strike since Wednesday night. Speaking on the situation, Air India spokesperson said that some flights had got delayed due to a sudden industrial situation at Mumbai by AIATSL employees. "We are assessing the situation and all efforts are being made to minimise delays or disruption," the spokesperson told NDTV. According to PTI, the employees went on a strike against non-payment of Diwali bonus. A senior official told the agency that the national carrier has called in its permanent employees to handle the ground handling operations at the Mumbai airport. "Negotiations are going on between the striking employees and the AIATSL management to resolve the issue," he said. The report suggests that at least 13 flights were delayed due to strike. "The delay was up to three hours," the official said. Several stranded passengers took to Twitter to raise their complaint. Anand Sivakumaran in a tweet said: "AirIndia Why did I book this fatichar airline. 676 from Kol to Mum delayed by 3 hrs. No announcement. No staff. Just an SMS five minutes before departure time. And with news of the strike in Mumbai wish someone would tell us if this bloody flight will take off or not."