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 mines and around 11 tonnes of weapons to Bangladesh when it crashed on Saturday night, minister Nebojsa Stefanovic said.

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

"I think the crew were Ukrainian but I don't have any information about that. They were not Serbian," Stefanovic told a news conference.

The plane had taken off from Nis airport in Serbia at around 8:40 pm (1840 GMT) on Saturday, carrying weapons owned by private Serbian company Valir, he said.

Greek media said it had requested clearance to make an emergency landing at Kavala airport but had not managed to reach it.

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

State-run TV said the army, explosives experts and Greek Atomic Energy Commission staff would approach the crash site once it was deemed safe.

"Men from the fire service with special equipment and measuring instruments approached the point of impact of the aircraft and had a close look at the fuselage and other parts scattered in the fields," fire brigade official Marios Apostolidis told reporters.

Search teams would go in when the area is deemed secure, he added.

A 13-strong special team from the fire brigade, 26 firemen and seven fire engines were deployed to the area but could not yet approach the crash site, local officials said.

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

Videos shared by eyewitnesses on social media showed the plane engulfed by a giant fireball as it hit the ground
Videos shared by eyewitnesses on social media showed the plane engulfed by a giant fireball as it hit the ground AFP / Sakis MITROLIDIS

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

Filippos Anastasiadis, mayor of the nearby town of Paggaio, told Open TV the aircraft had crashed "around two kilometres away from an inhabited area".

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

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

A local man, Giorgos Archontopoulos, told state broadcaster ERT television he had felt something was wrong as soon as he heard the aircraft's engine.

"At 2245 (1945 GMT) I was surprised by the sound of the engine of the aircraft," he said. "I went outside and saw the engine on fire."

The Ukrainian consul in Thessaloniki, Vadim Sabluk, visited the area on Sunday.

Athens News Agency said he had given the authorities the identities of the eight crew members and said the plane had been flying to Bangladesh.

The Serbian defence minister said the weapons shipment had been agreed with the Bangldeshi defence ministry "in accordance with international rules".

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