Maximilian Krah told reporters he would sack the member of his staff who was arrested on the spying charges and brought in front of an investigating judge on Tuesday evening.

The case has put the AfD on the back foot after it surged to become Germany’s second-most popular party ahead of European and local elections this year.

It has also fed wider anxieties over Europe as a target for Chinese and Russian spying operations. Germany had this week also arrested three people in a separate case about funnelling sensitive technology to China for military purposes.

Chinese Foreign Ministry spokesperson Wang Wenbin said on Tuesday reports of Chinese espionage in Europe were “hype” and “intended to discredit and suppress China”.

The latest case concerns a person identified by prosecutors only as Jian G., who is accused of passing information about discussions in the European Union legislature to Chinese intelligence and spying on the Chinese opposition.

The website of Krah, the AfD’s top candidate in June’s election to the European assembly, lists Jian Guo as one of his assistants. Krah said he learned of the arrest from the media and denied personal wrongdoing.

“I am and will remain the top candidate,” Krah told reporters. “It is now a matter of focusing the election campaign on European issues again and moving away from this very unpleasant matter.”

“It is a very serious accusation. After the arrest warrant was confirmed today, I will sack the employee in question today,” he added.

Chancellor Olaf Scholz visited China only last week for talks with the country’s leaders.

Germany has sought to “de-risk” the relationship with its largest trading partner, wary of tethering Germany to the Chinese economy after the invasion of Ukraine exposed Europe’s reliance on Russian gas and fuelled a cost-of-living crisis.

(Reporting by Matthias Williams and Alexander Ratz, Editing by Madeline Chambers and Timothy Heritage)