An Air India plane was forced to make an emergency landing after a suspected mid-air bomb threat earlier today.

Authorities said Flight AI 379, carrying at least 156 passengers, had departed Phuket International Airport around 9:30 am bound for Indira Gandhi International Airport in New Delhi, India.

The alarm was raised when a crew member discovered a note containing a bomb threat inside the bathroom wall of the Airbus A320.

The message read: 'F*** you all bomb.'

Air Traffic Control was immediately notified, and airport security activated the Airport Contingency Plan in response to the threat.

Flightradar24 tracking data showed that the aircraft circled over the Andaman Sea before returning to Phuket, where it landed safely at 11:37 am.

Passengers were initially not allowed to disembark as bomb disposal teams boarded the aircraft to inspect all baggage.

An investigation has been launched to identify the person responsible for the threat.

The incident comes just a day after the deadly crash of Air India Flight 171 on June 12, when a Boeing 787 Dreamliner crashed approximately 30 seconds after takeoff from Ahmedabad Airport, bound for London Gatwick.

Just one person from the 244 onboard survived.

The jet smashed into the doctors' hostel of BJ Medical College, sending debris, smoke and fire hundreds of feet into the air, and turning the whole area into what looked like a war zone.

As well as most on board, at least 50 people on the ground are said to have been killed and scores more injured.

Officials are now investigating the cause of the tragedy.