"We are already the targets of hybrid warfare. Including in space -- with systematic jamming of satellite navigation signals," Kallas told a conference in Brussels.

"There are risks to our satellites, the ground infrastructure, and our space industries from kinetic, electronic, and high-energy weapons. Espionage is a constant threat."

The former Estonian prime minister pointed as an example to Russia's firing of an anti-satellite missile and cyberattack on a space system just ahead of its 2022 invasion of Ukraine.

She sounded a warning to the EU's 27 nations, saying they must beef up their ability to respond to threats in space.

The EU needed to get better at monitoring and pinpointing those responsible, and could extend the bloc's mutual defence clause to cover space, she said.

"On retaliation, we are looking into punitive options," Kallas added, saying the EU could look to impose sanctions similar to those already applied to Russian intelligence agents over cyber attacks.

"We need to think about how best we can apply this to space."

While the EU faces aggressive rivals including Russia and China in space, Kallas insisted Europe must work together with the United States.

"The US is the EU's most important security partner on the ground. We must be allies in space too," she said.

"Space is clearly on the domestic US agenda. President (Donald) Trump said he wants to plant the stars and stripes on Mars."

The renewed call to bolster EU defences came after the bloc's space commissioner mooted bringing together the efforts of each member state into a coordinated "European Space Shield".