"China is not our adversary, but on security our relationship is under increasing strain," Kallas said ahead of meeting China's Wang Yi.

"Chinese companies are Moscow's lifeline to sustain its war against Ukraine. Beijing carries out cyberattacks, interferes with our democracies, and trades unfairly. These actions harm European security and jobs."

Wang's visit to Brussels -- following which he will head to Berlin and Paris -- comes some three weeks ahead of a summit between Chinese President Xi Jinping and the EU's top officials in Beijing.

As US President Donald Trump has rocked the major trading powers by unleashing a tariff war, the EU has opened the door to improving ties with China.

But instead of improvements, a trade spat has only deepened between Brussels and Beijing over alleged unfair practices by China.

And the 27-nation bloc is still railing against the flow of vital tech to Russia's military via China.

"Enabling war in Europe while seeking closer ties with Europe is a contradiction Beijing must address," Kallas said.

"In a volatile world, Beijing should use its growing strength to uphold international law."

In an effort to pressure Beijing, the EU has slapped bans on trading with a raft of Chinese firms accused of aiding Moscow's war effort.

But EU officials admit they have failed to shift Beijing from what it sees as its vital strategic partnership with Moscow.