The attacks targeted countries that have supported Ukraine in its struggle against the Russian invasion.

Two of the suspects were arrested in Huelva and Seville in southern Spain, while the third was detained in the Balearic Islands, a Guardia Civil police statement said.

They were arrested for “computer-related offences with terrorist intent” over a string of distributed denial-of-service (DDoS) attacks, which make websites or network resources unavailable by flooding them with malicious traffic.

The attacks were “organised by the Russian-linked hacker group called NoName057(16),” it said, without giving further details about what was targeted or the impact.

“The attacks were directed at public institutions and companies in strategic sectors in countries that took a position supporting Ukraine,” it said.

The police said the group’s main activity was staging DDoS attacks with “its own proprietary software called DDoSia which can be used by individuals who support its aims”.

Citing NoName’s manifesto, the police statement said the hacker group’s mission was to respond to “hostile and openly anti-Russian actions by western Russiaphobes”.

In mid-June, Swiss government websites were hit by a wave of DDoS attacks ahead of a summit aimed at seeking peace in Ukraine, in an operation claimed by NoName057(16).

They targeted federal government websites and those of organisations involved in the peace summit, Bern said.