German Chancellor Angela Merkel has expressed concern over the arrest of a German intelligence employee on suspicion of spying for US authorities.
Merkel spoke to reporters in Beijing on Monday during a visit to China.
She said if the allegations are true, it would be a serious matter.
German prosecutors arrested a 31-year-old man last Thursday.
German media say he allegedly handed over documents from a German parliamentary committee to US intelligence authorities over a 2-year period in exchange for 25,000 euros, or about 34,000 dollars.
The committee is looking into the issue of surveillance by the US National Security Agency.
German prosecutors are also investigating allegations that the NSA monitored Merkel's mobile phone.
Jul. 7, 2014 - Updated 22:47 UTC