Western leaders have reacted with scepticism to an announcement by China’s top diplomat that Beijing will put forward a peace proposal to bring an end to the war in Ukraine.

Wang Yi told the Munich Security Conference on Saturday that China “was not directly concerned in the conflict, but was not standing idly by” and would soon publish a position paper on how to find a political solution.

He said it would be based on principles already laid out by President Xi Jinping, including territorial integrity and “the sovereignty of all countries”.

In an apparent reference to the Russian army’s occupation of Ukraine’s Zaporizhzhia nuclear power plant, Europe’s largest, Wang also said China opposed “attacks on nuclear power stations”.

The Chinese initiative is expected to be unveiled in the coming week, around the February 24 anniversary of Russia’s full scale invasion of Ukraine.

Western leaders expressed concern about Sino-Russian co-operation.

Kamala Harris, US vice-president, said Washington was “troubled that Beijing has deepened its relationship with Moscow since the war began”.

She added: “Any steps by China to provide lethal support to Russia would only reward aggression, continue the killing, and further undermine a rules-based order.”

Antony Blinken, US secretary of state, said the west would be sceptical of a Chinese peace initiative that called for an immediate ceasefire.

“Who doesn’t want guns to stop firing? Except we have to be incredibly wary of the kind of traps that can be set,” he told the conference.

Russian president Vladimir Putin might decide that “because things are going badly” for him, his “best bet is to call for an immediate ceasefire” and create a “frozen conflict”, Blinken said.

“He will never negotiate the territory that he’s seized and meanwhile he’ll use the time to rest, to refit, to rearm and to reattack,” he warned.

US-China relations and the threat posed to European security by Russian aggression have dominated the Munich Security Conference, where senior foreign policy, defence and intelligence officials from across the west have gathered for three days of meetings on the eve of the first anniversary of the Russian invasion of Ukraine.

Western leaders have called on China to use its voice in the UN to condemn the war, but Beijing has maintained a studiously neutral public position.

Last year, just 20 days before the invasion, presidents Xi and Vladimir Putin struck what they called a “relationship without limits”.

German foreign minister Annalena Baerbock said of the Chinese proposal that “we have to exploit every chance for peace”.

“It’s good . . . that China sees it as its responsibility, as a member of the UN Security Council, to stick up for world peace,” she said.

But she warned that Germany would not accept the Chinese proposal if involved a suspension of western arms supplies to Ukraine.

“If Russia stops fighting then this war is over,” she said. “But if Ukraine stops defending itself . . . then Ukraine is over. And we can’t accept this.”

Any peace proposal must be based on a “recognition of the sovereignty and territorial integrity of every country”, she added.

Wang also used his Munich speech to criticise Washington for its response to the recent flight of a Chinese balloon into US airspace. Washington’s decision to shoot the balloon down off the Atlantic coast earlier this month was “hysterical and absurd”, he said.

He added that to maintain peace across the Taiwan Strait, Taiwanese independence forces must be opposed.

The US has said it suspects the balloon was used for surveillance after it spent a week flying over the US and Canada. Beijing has denied this.

“Across the globe there are many balloons from many countries. Do you want to shoot down every one of them?” Wang said.

“It did not show that the US is strong. On contrary, it showed the opposite. We urge the US not to do such preposterous things in order to divert attention from its domestic problems.”

Western officials now believe the balloon may have drifted off its intended course. Biden said on Friday that he aimed to speak with Chinese president Xi Jinping to “get to the bottom” of the incident, although he has not specified when.