Two pieces, including a large spherical object, were found by herders over the weekend, while another was discovered in the courtyard of a residential house on Monday, said the region's head Sholban Karaa-ool, warning people not to touch any metal debris.

Regional sanitation officials "inspected the spot where two pieces of the spacecraft were found in the Ulug-Khem district, on the side of the mountain and near a yurt," Kara-ool said on his official website.

"Another small piece was found in the yard of a house in the Eilig-Khem village," he said.

"Compatriots, if you find metal objects, don't touch them," he said.

The unmanned cargo ship Progress MS-04 launched Thursday with over 2.5 tonnes of food, water and equipment for the International Space Station, but ground control in Russia's Roscosmos space agency lost control several minutes into the flight.

The agency is currently investigating the reasons behind the crash, which could have been caused by an engine failure on the third-stage rocket, according to sources in the industry cited by Russian media.