A man looks at wreckage near the scene of a AN-148 plane crash in Stepanovskoye village, about 40 kilometres from the Domodedovo airport, Russia. Picture: AP Photo/Alexander Zemlianichenko

Moscow - More than a thousand body parts and hundreds of plane fragments have been recovered from the crash site of a Russian airliner, but the cause of the accident remains a mystery.

As of Tuesday morning, "more than 1 400 fragments of the bodies of the deceased and about 500 fragments of the aircraft have been recovered," the Emergency Situations Ministry said.

The Saratov Airlines aircraft, en route to the Russian city of Orsk near the border with Kazakhstan, crashed just minutes after take-off from Moscow's Domodedovo Airport on Sunday.

All 65 passengers and six crew members were killed. The plane exploded upon hitting the ground, federal investigators have said.

Read more: WATCH: Several children killed after Russian plane ‘breaks up in air’

Emergency workers have been scouring an area of 30 hectares around the crash site, a snow-covered field in the Moscow region, day and night for the recovery operation and investigation, according to the ministry.

"The work is being conducted around the clock, in three shifts," it said, adding that about a thousand people have been working at the site.

Authorities suspect that the crash was caused by human error, a technical malfunction or complications due to bad weather. Over the past week, Moscow has been hit by the heaviest snowfall in a century.

The regional jet, a Russian-assembled An-148, was eight years old. The Ukrainian and Russian manufacturers of that type of aircraft pledged to assist in the investigation.

The ministry said that the families of the victims will receive at least the equivalent of about 50,000 dollars each.

The airline's insurance will provide 2 million roubles (35 000 dollars), and the Moscow region's government 1 million, the ministry said in a statement.