The plane had reportedly requested clearance to make an emergency landing at nearby Kavala airport, but did not manage to reach it.

A cargo aircraft crashed near Paleochori Kavalas in northern Greece late Saturday.

According to Greek Civil Aviation authorities, the plane operated by a Ukraine-based airline was traveling from Serbia to Jordan.

The pilot had reportedly requested clearance to make an emergency landing at nearby Kavala airport due to an engine problem, but did not manage to reach it.

Communication with the plane ceased almost immediately afterwards.

The aircraft was already in flames before it crashed, people close to the crash site told local media.

Ongoing explosions at the crash site, say officials

State-run broadcaster ERT television reported that it was an Antonov aircraft owned by a Ukrainian company.

The An-12, a Soviet-built turboprop aircraft, was operated by cargo carrier Meridian.

The plane crashed on farmland close to two villages that are part of the Paggaio municipality.The fire service said in a statement that it has cordoned off the crash site.

Local officials said 15 firefighters and seven fire engines had been deployed to the area. More rescuers were on their way.

But the firefighters were finding it difficult to approach the site because of the ongoing explosions, officials said.

"We were hearing explosions until a few minutes ago," Filippos Anastassiadis, mayor of the municipality of Paggaio, told the Associated Press. "I am about 300 meters from the site of the crash."

'Treating the cargo as dangerous material'

There is no official information about the number of people onboard the plane.

But ERT reported that the plane was carrying eight people and that its cargo "was dangerous," including munitions.

Police were asking people to leave the area and journalists at the scene to wear masks, the report added. Inhabitants of the two localities closest to the site were told to keep their windows shut all night, to not leave their homes and to wear masks.

The special disaster response unit was also investigating the scene.

"We are treating the cargo as dangerous material," a fire brigade official told Reuters news agency.

ERT reported that army and explosive experts were en route to the site. But they are not expected to start working before dawn.

Experts from Greece's Atomic Energy Commission will join them.