Russian officials have rejected accusations that they endangered astronauts aboard the International Space Station by conducting a weapons test that created more than 1,500 pieces of space junk.

US officials on Monday accused Russia of destroying an old satellite with a missile in what they called a reckless and irresponsible strike. The debris could do major damage to the space station as it orbits at 17,500mph.

Astronauts now face a risk four times greater than normal, Nasa administrator Bill Nelson told Associated Press.

The test demonstrates that Russia, “despite its claims of opposing the weaponisation of outer space, is willing to... imperil the exploration and use of outer space by all nations through its reckless and irresponsible behaviour,” United States secretary of state Antony Blinken said.

The Russian space agency Roscosmos would not confirm or deny that the strike took place, saying only that the “unconditional safety of the crew has been and remains our main priority” in a vague online statement.

The Russian Defence Ministry yesterday confirmed carrying out a test and destroying a defunct satellite, but insisted “the US knows for certain that the resulting fragments, in terms of test time and orbital parameters, did not and will not pose a threat to orbital stations, spacecraft and space activities”.

Foreign minister Sergey Lavrov claimed it is hypocrisy to say Russia creates risks for peaceful activities in space.

Once the situation became clear on Monday morning, the four Americans, one German and two Russians on board the space station were ordered to immediately seek shelter in their docked capsules.

They spent two hours in the two capsules, finally emerging only to have to close and reopen hatches to the station’s individuals labs on every orbit, every 90 minutes, as they passed through the debris.

Nato secretary-general Jens Stoltenberg said: “This was a reckless act by Russia to actually shoot down and destroy a satellite as part of a test of an anti-satellite weapon system.”

He said it was of additional concern “because it demonstrates that Russia is now developing new weapons systems that can shoot down the satellites, can destroy important space capabilities for basic infrastructure on Earth, like communications, like navigation, or like early warning of missile launches.”

Nasa Mission Control said the heightened threat could continue to interrupt the astronauts’ scientific research and other work.