China on Tuesday canceled a planned visit by the European Union’s foreign policy chief that was scheduled for next week without providing a specific reason.

High Representative for Foreign Affairs Josep Borrell was initially due to visit Beijing in April for the annual EU-China strategic dialogue with Chinese Foreign Minister Qin Gang, but that was delayed after Borrell tested positive for Covid-19.

On Wednesday, an EU foreign affairs spokesperson confirmed to CNBC that Borrell’s team had been told by their Chinese counterparts the new dates of July 10-11 were no longer possible and an alternative would need to be found. Topics under discussion were set to include human rights and Russia’s war in Ukraine.

Chinese foreign ministry spokesperson Wang Wenbin declined to provide a reason for the cancellation at a briefing Wednesday, but added: “We welcome High Level Representative Borrell to visit China at the earliest time convenient to both sides,” according to a Reuters report.

CNBC has contacted China’s Ministry of Foreign Affairs for comment.

The cancellation, or possible postponement, comes ahead of a scheduled visit to Beijing by U.S. Treasury Secretary Janet Yellen on Thursday.

China on Monday announced new export restrictions on two metals, germanium and gallium, which are key to the manufacturing of semiconductors and electronics and have uses from military equipment to mobile phones.

The news has driven prices of the metals higher while also pushing companies into a scramble to shore up supplies, according to Reuters.

In recent years, the U.S. has increasingly used export restrictions and trade blacklists against China as it seeks to curb the growth of its technological power.

Former Chinese Vice Commerce Minister Wei Jianguo told the China Daily newspaper the latest measures on Monday were “just the beginning” and that “if the high-tech restrictions on China become tougher in the future, China’s countermeasures will also escalate.”

“It’s weaponizing that rare earth and critical minerals supply chain,” Rebecca Harding, trade and political risk specialist and senior fellow at the British Foreign Policy Group, told CNBC’s “Squawk Box Europe” on Wednesday.

“[There] is an element of mutually assured destruction because you can’t manufacture chips if you haven’t got the supply chains. But these export controls are going to be fairly limited,” she said.

She added the measures could be seen as retaliatory for actions of not just the United States but also the Netherlands, a crucial semiconductor machinery hub, which last week announced new export restrictions on advanced semiconductor equipment. There is unlikely to be “any imminent rowing back,” Harding added.