Russia may fail to fulfill its obligations in delivering crews to the International Space Station after Wednesday's accident with Russia's Progress M-12M space freighter, a source in Russia's space industry said.

The space freighter fell in South Siberia's Altai Republic on Wednesday after failing to separate from the Soyuz-U carrier rocket, the first loss of the Progress freighter in the history of Russia's space industry. A rocket engine failure is believed to have caused the accident.

"The scheduled launches of the [Soyuz] rockets are likely to be suspended because of the space freighter accident... until the reasons [of the accident] are established," the source said.

This means that members of the International Space Station's crew are likely to stay at the station longer than planned and that the new crew will not be able to replace them on schedule, he said.

After the retirement of the U.S. shuttle fleet earlier this summer, Russian Soyuz craft became the only way for astronauts to reach the ISS until at least the middle of the decade. NASA is paying its Russian counterpart Roscosmos more than $1 billion for crew transport services over the next four years.

The Soyuz-U carrier rocket blasted off from the Baikonur Space Center in Kazakhstan and was scheduled to separate at 5:09 p.m. Moscow time [13:09 GMT]. The source said the engine failure made it impossible for the spacecraft to achieve the required orbital velocity.

The Progress freighter was insured for 3 billion rubles ($103 million) by the Russian Insurance Center company, its representative said.

The space freighter was to deliver 2.7 tons of food, medical and scientific equipment, and other items to the ISS, the source said.

Russian space agency Roscosmos promised that the failure to deliver food to the ISS would not affect its crew, saying that food stocks on board the ISS were enough to sustain the crew for a "long time."

Russian cosmonauts Andrei Borisenko, Alexander Samokutyayev and Sergei Volkov, as well as NASA astronauts Ronald Garan and Michael Fossum and Japanese astronaut Satoshi Furukawa are currently working on the ISS.

The next Progress cargo ship will not fly to the ISS before late September-early October, Gennady Raikunov, head of the Central Scientific Research Institute of Machine Manufacturing, said.

A special commission was created from representatives of Roscosmos and other space industry organizations to investigate the accident.

Russia has carried out more than 130 successful launches of Progress space freighters since they entered service in 1972.

Wednesday's accident is the second spacecraft loss for the Russian space industry in within a week. On August 18, the Express AM-4 telecommunications satellite failed to separate from the Proton-M carrier rocket and could not reach the designated orbit.