Beijing condemned new European Union sanctions against two Chinese tech companies over alleged cyberattacks as "unlawful" on Tuesday, urging Brussels to "rectify its erroneous practices".

The EU Council said on Monday it had sanctioned China-based Integrity Technology Group and Anxun Information Technology for helping to hack "critical infrastructure" and tens of thousands of devices across the European Union.

It also sanctioned Anxun's two Chinese co-founders and Iranian hacking group Emennet Pasargad.

European citizens and companies are banned from providing funds to the companies, and the two Chinese founders are forbidden from "entering or transiting through EU territories", a Council statement said.

The UK also sanctioned China-based Integrity and Anxun in December for "reckless and indiscriminate cyberattacks".

"China firmly opposes the EU's unlawful, unilateral sanctions against Chinese entities and urges the EU to rectify its erroneous practices," foreign ministry spokesman Lin Jian told a news briefing.

Beijing urged Brussels to cooperate in a "responsible and constructive manner to safeguard peace, stability and prosperity in cyberspace".