The Progress is an automated, unpiloted version of the Soyuz spacecraft. Progress cargo ships have been used for years to supply both the International Space Station and the former Russian Mir space station. NASA/Reuters

An unmanned Russian supply ship bound for the International Space Station failed to reach its planned orbit Wednesday, and pieces of it fell in Siberia amid a thunderous explosion, officials said.

A brief statement from Roscosmos, Russia's space agency, did not specify whether the Progress supply ship that was launched from the Baikonur cosmodrome in Kazakhstan had been lost. But the state news agency RIA Novosti quoted Alexander Borisov, head of a the Choisky region in Russia's Altai province, as saying pieces of the craft fell in his area some 1,500 kilometres northeast of the launch site.

"The explosion was so strong that for 100 kilometres glass almost flew out of the windows," he was quoted as saying.

Borisov said there were no immediate reports of casualties.

The Russian Emergencies Ministry could not be reached for comment. A Roscosmos media officer who refused to be identified said the agency had no immediate comment.

Roscosmos said the third stage of the rocket firing the ship into space failed a few minutes into the launch. The ship was carrying more than 2.5 tons of supplies, including oxygen, food and fuel. Since the ending of the U.S. space shuttle program this summer, Russian spaceships are a main supply link to the space station.

44th Progress mission

It was the 44th Progress to launch to the International Space Station.

Roscosmos said the accident "would have no negative influence" on the International Space Station crew because its existing supplies of food, water and oxygen are sufficient.

In the United States, NASA said the rocket appeared to function flawlessly at liftoff, which occurred right on time, but there was a loss of contact with the vehicle just over five minutes into the flight.

On NASA TV, Russian officials said the upper stage did not separate from the supply ship and that on two subsequent orbits controllers tried to contact the supply ship — in vain. Two hours after the mishap, Russian Mission Control told the space station crew: "We'll try to figure it out."

NASA is counting on Russia as well as Japan and Europe to keep the orbiting outpost stocked, now that the space shuttles are no longer flying. The shuttle program ended in July with the Atlantis mission; a year's worth of food and other provisions were delivered.

Late this year, a commercial company in California plans to launch its own rocket and supply ship to the space station. NASA is encouraging private enterprise to make station deliveries.

There are six astronauts aboard the International Space Station, which orbits 350 kilometres above the Earth. They are Russians Andrei Borisenko, Alexander Samokuyayev and Sergei Volkov, Americans Michael Fossum and Ronald Garan and Satoshi Furukawa of Japan.

Space station well-supplied: NASA

"The supplies aboard the space station are actually pretty fat" after the resupply mission by space shuttle Atlantis in July, NASA spokesman Kelly Humphries said from Houston. "So we don't anticipate any immediate impact to the crew."

Humphries stressed that NASA was waiting to get more details from Russian space officials on what actually happened.

The Interfax news agency cited a Russian space analyst, Sergei Puzanov, as saying the space station had supplies already aboard that could last two to three months and "the situation with the loss of the Progress cannot be called critical."

In July of 2010, a Progress supply ship failed in its first automatic docking attempt due to equipment malfunction, but was connected with the orbiting laboratory two days later.