UK police have charged two men with spying for China, including one reported to have worked as a parliamentary researcher for a prominent MP in the governing Conservative Party.
Three people also suspected of spying for China and arranging to transfer information on technology with potential military uses were also arrested in Germany on Monday.
Anxiety has mounted across Europe about China's alleged espionage activity and Britain and Germany have become increasingly vocal about their concerns in recent months.
The two British men, aged 32 and 29, were charged with providing prejudicial information to China in breach of the Official Secrets Act, and will appear in court on Friday.
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READ NOW"This has been an extremely complex investigation into what are very serious allegations," said Commander Dominic Murphy, head of the Counter Terrorism Command at the UK's Metropolitan Police.
The Chinese embassy in London said the allegation that China was trying to steal British intelligence was "completely fabricated".
"We firmly oppose it and urge the UK side to stop anti-China political manipulation and stop putting on such self-staged political farce," an embassy spokesperson said in a statement.
One of the men was named by police on Monday as Christopher Cash who The Sunday Times reported as being arrested in September for spying while working as a researcher in parliament for Conservative MP Alicia Kearns, chair of the Foreign Affairs Committee.
The government has said Chinese spies are targeting British officials in sensitive positions in politics, defence and business as part of an increasingly sophisticated spying operation to gain access to secrets.
Meanwhile in Germany, prosecutors said three citizens were accused of having acted for Chinese intelligence since some point before June 2022.
They are also suspected of violating German export laws by exporting a special laser without permission.
One of the suspects, identified only as Thomas R in line with German privacy laws, was allegedly an agent for an employee of China's Ministry of State Security and procured information in Germany on "militarily usable innovative technologies" for that person, federal prosecutors said in a statement.
To do that, prosecutors said, he used Herwig F and Ina F, a couple who own a company in Duesseldorf that was used to contact and work with German researchers.
The couple allegedly set up a research transfer agreement with an unidentified German university, the first step in which was to draw up a study for a Chinese partner on the technology of machine parts that could be used for powerful ship engines, including those in battleships.
Thomas R's handler at the MSS was behind the Chinese partner and the project was financed by the Chinese state, prosecutors said.
At the time of the arrests, the suspects were in negotiations on further research projects that could be useful for expanding China's naval combat strength, they added.
Interior Minister Nancy Faeser said Monday's arrests were "a great success for our counterespionage."
"We are keeping an eye on the significant danger from Chinese espionage in business, industry and science," she said in a statement.
China has firmly rejected the accusation that it is carrying out spying activities, its Berlin embassy said.
"We call on Germany to desist from exploiting the espionage accusation to politically manipulate the image of China and defame China," a statement said.
with AP