Russia has grounded its Soyuz rockets after a space ship carrying tonnes of cargo for the International Space Station (ISS) crashed into Siberia shortly after blast-off, an official said on Thursday.
The failed launch of the unmanned Progress capsule was a spectacular blow for Russia which had proudly become the sole nation capable of transporting humans to the ISS after the withdrawal of the US space shuttle in July.
Emergency services blocked access to the site of the crash in the Altai region of Siberia, state television said, amid fears the space freighter could have dumped highly-toxic fuel in the area.
"A decision has been taken to halt the launch of Soyuz carrier rockets until the reasons for the accident become clear," an unnamed Russian official told the Interfax news agency.
There was no immediate official comment on the report from the Russian space agency Roskosmos. Soyuz rockets are used to launch the unmanned Progress cargo vehicles as well as the Soyuz manned capsules for the ISS and are the backbone of the Russian space programme.
The next manned flight to the ISS -- currently staffed by a six-person multinational crew -- is scheduled for September and a cargo vessel with new supplies is due to take off in October.
Igor Lisov, the space expert of specialised journal Novosti Kosmonavtiki, played down the implications for global space exploration, saying that the grounding was normal practice after an accident.
"The cause of the accident will be established soon. After they have found out and eliminated the causes, the Soyuz will fly again, undoubtedly," he told AFP.
The ISS depends on the Progress deliveries for basic supplies such as food and water but both Russian and US officials took care to dispel suggestions that the accident may prompt an emergency evacuation of the ISS crew.
Space officials from both sides said the team -- which besides three Russians includes two US astronauts and a spaceman from Japan -- had at least two months of supplies of food and other basics.
But Roskosmos removed all reference to future missions from its official website, leaving an ominous-looking black space where the listing is usually found.
Roskosmos said in a statement Thursday it was in contact with NASA about "resolving questions" related to supporting the ISS as well as future manned and freight launches.
It also announced a full review of its rockets and the creation of a working group that would "control the execution of the manned space flight programme".
Russian news agencies said space officials had also informed ISS commander Andrei Borisenko of the loss of the supply craft and that the team took the news "with understanding."
Local officials said fragments of the craft crashed into Russia's Siberian region of Altai on the border with Mongolia and China -- a remote region of soaring mountains and poorly accessible by road.
"The explosion was so powerful that it shattered windows nearly 100 kilometres (60 miles) away," said the region's Choya district head Alexander Borisov.
Emergency services are now on their way by helicopter to the site after initially being hampered by heavy rain. There have been no reports of casualties, despite fears people could have been pine-nut picking in the area.
The Interfax news agency quoted a space official as saying that the Progress contained one-and-a-half tonnes of highly toxic fuel but it was unclear how much had burned up on intact and what quantity entered the soil.
The Progress was the fourth failed launch of a capsule or satellite by Russia since December last year when three satellites for its prized new GLONASS system crashed into the Pacific Ocean after launch.
This was followed by the loss of a new military satellite in February while only last week a satellite for Internet and digital television across Russia was lost after being put into the wrong orbit after launch.
That failure led to Roskosmos grounding its Proton-M carrier rockets.
"The series of launch accidents points to a deep crisis," the respected Kommersant business daily said on its front page.
The speaker of the Russian lower house of parliament, Boris Gryzlov, called for a debate on the spate of failures. "It is right to ask whether this is down to systemic issues or a fateful coincidence," he said.