The Centre has decided to deploy more air marshals to bolster security on passenger aircraft on “sensitive” international and domestic routes amid the rising number of bomb threats on flights, sources in the Union home ministry said on Wednesday.

Over the past two days, at least 12 bomb threats had been received by various airlines on domestic and international routes and all of them were found to be hoaxes. Some flights were diverted while some airlines had to re-screen all the passengers, leading to major delays and inconvenience.

“The decision to increase the number of air marshals has been taken after assessment of growing threats and getting inputs from central intelligence agencies and other stakeholders,” said a Union home ministry official.

Presently, one or two armed security personnel — specialised in anti-terror and anti-hijacking measures — are deployed as air marshals especially on sensitive international routes, besides a few domestic routes on Jammu and Kashmir and northeastern states.

In India, flight marshals were introduced in 1999 after the hijacking of Air India flight IC-814 by militants who took it to Kandahar. Sky marshals travel in passenger aircraft.

The presence of sky marshals is intended to deter and respond to potential threats to civil aviation, ensuring the safety of passengers and crew.

The Union home ministry on Wednesday sought a report from the civil aviation ministry after a series of bomb threats were received by multiple airlines over the last 48 hours, disrupting services.

Sources said the home ministry directed the civil aviation ministry, Central Industrial Security Force (CISF), Bureau of Civil Aviation, National Investigation Agency (NIA) and the Intelligence Bureau (IB) to submit a detailed report on bomb threats that have been received recently.

“The ministry has instructed all concerned security agencies in the aviation sector to submit a detailed report at the earliest. The investigation will be monitored by the central intelligence agency to find out if it was a conspiracy to damage the reputation of the Indian aviation sector,” a ministry official said.

A preliminary probe revealed that most of the social media accounts that issued the fake bomb threats were found to be operating from outside India. “These accounts have been suspended. Cyber security agencies are also on alert and are tracking social media accounts that are linked to these hoax threats,” the official added.

Sources said the civil aviation ministry held meetings with the Bureau of Civil Aviation, the CISF and other senior officials associated with airport security over the bomb threat.

On Tuesday, seven flights, including an Air India flight headed to Chicago, received bomb threats. After thorough checking, these threats were found to be fake. On Wednesday, two flights received bomb threats and they were turned back and diverted for security clearance.

On Monday, two IndiGo and one Air India flight received hoax threats. These included Air India flight AI119 from Mumbai to New York’s JFK Airport, an IndiGo flight 6E1275 bound for Muscat, and flight 6E56 heading to Jeddah.