An unmanned Russian rocket carrying three navigation satellites has crashed shortly after lift-off from the Russian-leased Baikonur launch facility in Kazakhstan, spilling its highly toxic propellant.
Russian state-run television Rossiya-24 showed footage on Tuesday of the Proton-M booster rocket veering off course seconds after lift-off. It fell apart in flames in the air and crashed in a big ball of fire near the launch pad in the territory of Baikonur.
There were no reported injuries.
Russian-based Interfax news agency quoted an unnamed source as saying launch facility personnel were in bunkers when the rocket lifted off.
Kazakhstan's space agency Kazcosmos said the accident at launch pad No. 81 had taken place at 8:38 am (0238 GMT).
"According to the preliminary estimates from the Russian side, there is no destruction and there are no casualties," Kazcosmos said.
Quoting a Kazakh security source, Interfax said around 170 tonnes of heptyl, a highly toxic rocket propellant, were burning at the scene.
The agency said Kazakh emergency authorities were considering evacuating nearby towns in the sparsely populated area because of the potential health threat.
Kazakhstan's government will hold an emergency meeting later on Tuesday, a government spokesman said.
The estimated loss from the three satellites, meant for Russia's troubled Glonass satellite navigation system, was about $200m, Rossiya-24 reported.
Russia's state-run RIA news agency said the cause could have been a problem with the engine or the guidance system.
Russia plans to spend more than $9.1bn by 2020 on Glonass, its answer to the US GPS system.
The system, first conceived by the Soviet Union more than 40 years ago, has been plagued by previous failed launches, including one in 2010 in which three satellites were also lost, and by suspicions of corruption and embezzlement.
Its chief designer was dismissed last year during a fraud investigation.
The Proton rocket, known at the time under its UR-500 code, made its first test flights in the mid-1960s.
It was originally designed as an intercontinental ballistic missile to carry a nuclear warhead targeting the Soviet Union's Cold War foe the United States. But it was never deployed as a nuclear weapon.
Several crashes of Proton rockets accompanied by spills of heptyl have led to temporary strains in relations between Russia and Kazakhstan.
Russia is increasing spending on space and plans to send a probe to the moon in 2015.
However, the pioneering programme that put the first man in space in 1961 has been plagued in recent years by setbacks, including botched satellite launches and a failed attempt to send a probe to a moon of Mars.