Police have arrested a 19-year-old youth hailing from Bihar, who allegedly made hoax calls over the past two years to various airline offices here threatening to hijack planes if the authorities failed to release 26/11 accused Ajmal Kasab.

The calls made by accused Vikas Yadav led to delay and cancellation of flights, the police said.

The Crime Branch of the Mumbai Police claimed that Yadav was earlier arrested by the Gujarat Police in 2011 for a similar offence when he claimed to be gangster Dawood Ibrahim and threatened to blow up Rajdhani Express and Sabarmati Express.

“He used to call up the airline companies, calling himself Kasab, and demand the release of Kasab. He would say that his men were already on the plane and would hijack it. It would lead to an entire security drill on-board, which meant evacuation of passengers, safety checks, etc. This would delay the flights,” Deputy Commissioner of Police (Detection) Ambadas Pote said at a press conference here on Saturday.

“Four such cases were registered in Mumbai — one in January 2011, then in May 2012, October 2012 and the most recent one on January 4, 2013. Since the accused used to name Kasab, the Police Commissioner found the matter serious and handed over the probe to the Crime Branch,” Mr. Pote said.

The police have seized six cell phones and five SIM cards from his parents’ house in Vapi, Gujarat. It has been established that the calls were made from those numbers, he said.

He said the accused would be sent for medical examination to verify if he was suffering from any mental illness since the motive behind the calls was not yet clear. “He has confessed that he made the calls. Asked why he did it, he has no answer,” Mr. Pote said.