A cargo plane operated by a Ukrainian airline carrying munitions from Serbia to Bangladesh has crashed in northern Greece, killing everyone on board.

Residents reported seeing a fireball and hearing explosions for two hours after the Antonov aircraft came down on farmland near the city of Kavala.

Debris from the Soviet-era An-12, operated by Ukrainian-based airline Meridian, was strewn across fields.

"This is not related to Ukraine or Russia," said Meridian's general director, Denys Bogdanovych.

Greek authorities said there were eight people on board. The were all Ukrainian citizens, the country's foreign ministry said.

None had survived, Meridian confirmed.

Serbia's defence minister, Nebojsa Stefanovic, said the plane was carrying 11.5 tonnes of products - including mortar and training shells - made by Serbia's defence industry.

The cargo was owned by Serbian company Valir and had been ordered by Bangladesh's defence ministry, he added.

Greek media initially reported the plane was carrying 12 tonnes of "dangerous materials", mostly explosives.

State broadcaster ERT reported that army and explosives experts were on their way to the site.

Greece's Civil Aviation authority said the pilot managed to alert authorities about a problem in one of the plane's engines.

It added that he was given the choice of landing at airports in either Thessaloniki or Kavala and he opted for Kavala, which was closer, saying he had to make an emergency landing.

However, communication with the plane ceased almost immediately afterwards and the aircraft crashed about 40km west of the airport.

"We were hearing explosions until a few minutes ago," Filippos Anastassiadis, mayor of the municipality of Paggaio, said a little over an hour after the plane came down.

"I am about 300m from the site of the crash."

One of Mr Anastassiadis's deputies told ERT that explosions were heard for two hours following the crash.