Kavala: All eight crew members of a cargo plane that crashed near the Greek city of Kavala died in the accident, Serbia's defence minister said on Sunday.

The Ukrainian-operated Antonov An-12 was carrying around 11 tonnes of weapons, particularly mines, to Bangladesh when it crashed on Saturday night, minister Nebojsa Stefanovic said.

"Sadly, according to the information we have received, the eight members of the crew died in the crash," Stefanovic told a news conference.

Videos shared on social media by eyewitnesses showed the plane engulfed by a giant fireball as it hit the ground.

Denys Bogdanovych, general director of Meridian, the Ukrainian cargo airline operating the plane, told German broadcaster Deutsche Welle the crew were all Ukrainian. He gave no information about the cargo.

The plane had taken off from Nis airport in Serbia at around 8:40 pm (1840 GMT) on Saturday, carrying "around 11 tonnes of military industry goods", namely mines, from private Serbian company Valir to the Bangladeshi defence ministry, Stefanovic said.

It had requested clearance to make an emergency landing at the airport in Kavala, northern Greece, but had not managed to reach it.

Eyewitnesses said on Saturday they saw the aircraft on fire and heard explosions.

Video footage from a local channel showed signs of impact in a field and the aircraft in pieces scattered over a wide area.

- Toxic fumes -

Greek rescue services were using a drone on Sunday to monitor the wreckage as fears about the toxicity of the cargo were forcing them to keep at a distance.

Biological and chemical weapons experts from the army were expected to comb the crash site during the day, the civil protection ministry said.

Villagers were forbidden to go into the fields near the crash until the authorities could remove the wreckage and unexploded ammunition.

People living within a two-kilometre (1.2-mile) radius of the crash site were asked to stay inside and wear face masks on Saturday night.

Two firemen were taken to hospital early on Sunday with breathing difficulties because of toxic fumes.

Fire brigade official Marios Apostolidis told reporters staff with "special equipment and measuring instruments" had inspected the point of impact and fuselage.

- Fireball -

Athens News Agency (ANA) said an investigation would be launched into the cause of the accident.

"We heard a deafening noise (and saw) a fireball approaching the ground. Then came the explosion," Sofia, a mother of three from the nearby village of Antifilipi told ANA.

Local man Giorgos Archontopoulos told state broadcaster ERT he sensed something was wrong as soon as he heard the aircraft overhead.

"At 10:45 pm I was surprised by the sound of the plane's engine," he said. "I went outside and saw the engine on fire."

"If it had crashed some seconds earlier, it would have hit our house," 80-year-old Michalis Emmanouilidis, visibly shaken, told ANA.

The Ukrainian consul in Thessaloniki, Vadim Sabluk, visited the area on Sunday and the Greek foreign ministry expressed its "sincere condolences" to the victims' families.

ANA said Sabluk confirmed the identities of the crew and the plane's destination.

Serbia's defence minister said the weapons shipment was not linked to Russia's war in Ukraine.

"Unfortunately some media have speculated that the plane was carrying weapons destined for Ukraine but that is completely untrue," he said.