China said on Monday that a Chinese woman who helped with the German weekly Die Zeit's coverage of the protests in Hong Kong was working for the newspaper without permission and has been arrested on suspicion of "causing a disturbance".
Germany expressed concern about the arrest of Zhang Miao last week, saying it was "worrying news for the German government".
Thousands of protesters have taken to the streets of the Chinese-controlled city of Hong Kong in recent weeks, demanding that Beijing stand by its promise of introducing universal suffrage at elections for its leader in 2017. China has labelled the protests illegal.
Chinese Foreign Ministry spokesman Hong Lei said Zhang was suspected of "causing a disturbance".
"This person did not obtain the status of a Chinese employee for the Beijing-based German reporter in accordance with Chinese regulations," Hong told a daily news briefing.
"The relevant Chinese authorities are handling the case in accordance with the law and the rules. This person is a Chinese citizen and should fulfil her obligations as a citizen and cooperate with the public security authorities' investigation."
The Hamburg-based weekly reported last Thursday that Zhang, who was assisting the newspaper's main correspondent in China, was detained on Oct. 2 and accused of inciting public discontent.
Martin Schaefer, a spokesman for the German foreign ministry, said last week that the German embassy in Beijing was in touch with Chinese authorities on the matter with the goal of clearing up the accusations and trying to ensure Zhang would be able to continue her work.