Greek police believe a mechanical fault may have caused a helicopter to crash moments before it was due to land on the island of Sifnos, killing a British couple on honeymoon and the pilot.

Authorities were focusing on Tuesday on the “strange noise” the aircraft, a privately chartered Bell 206, is reported to have made before falling to the ground and exploding on impact.

“We can confirm that two passengers, Marie Ebert and Alexander Cromie, died in the incident on Monday evening,” a police officer said.

The London-based Ebert and Cromie, aged 30 and 31 respectively, had selected Sifnos to spend their honeymoon after recently marrying.

Officials in Syros, the Aegean’s administrative centre, identified the pilot as Giorgos Raikos, 53, saying he was a former air force officer and “extremely experienced”.

One well-placed source said: “The focus of the inquiry is now on the helicopter and possible engine failure. What has happened is nothing short of a tragedy.”

The – deputy mayor of Sifnos, Manolis Fountolakis, told Greek TV: “People in the area have testified hearing the helicopter making a noise, a strange noise, probably a mechanical fault in the air and because the propeller was doing something strange.”

CCTV footage is also being studied of the aircraft spiralling out of control as it approached the island’s helipad near the village of Exambela.

Greece’s public broadcaster, ERT, quoted Antonis Zambelis, a local resident, as saying: “The helicopter crashed about 50 metres away from houses with people inside and about 50 metres from the landing spot next to the Panayia tis Vrysis monastery.”

Thick plumes of smoke engulfed the crash site after the helicopter ignited in a fireball. Rescue workers who scrambled to douse the flames subsequently discovered the remains of all three victims.

Greece’s ministry of infrastructure and transport was coordinating the inquiry on Tuesday as senior law enforcement officials converged on Sifnos.

The island’s mayor, Maria Nadali, said: “We are shocked and are trying to manage, together with the right services, the consequences of this incident next to the helipad.”

Hiring private helicopters has become ever more popular in Greece, with tourists increasingly chartering them to hop between islands in the Ionian and Aegean seas.

Once considered remote, Sifnos is about 120 miles (195km) south-east of Athens and takes several hours to reach by ferry.