BEIJING — The visit to China by Chancellor Angela Merkel of Germany was supposed to focus on business, but financial matters were overshadowed Monday by a spy scandal at home — reportedly involving the United States — and China’s wartime history with Japan.

At a news conference with Prime Minister Li Keqiang, Ms. Merkel raised questions about Germany’s relationship with the United States when asked about allegations that an employee of her country’s Federal Intelligence Service was working for Washington. “If the allegations are true, it would be a clear contradiction as to what I consider to be trusting cooperation between agencies and partners,” Ms. Merkel said. She added, “If the reports are correct it would be a serious case.”

The arrest of the intelligence employee has caused an uproar in Germany, along with demands for an explanation from the Obama administration. The episode follows revelations by Edward J. Snowden, a former National Security Agency contractor, that the N.S.A. had bugged Ms. Merkel’s cellphone and monitored the electronic activities of millions of Germans.

In Berlin on Monday, the United States Embassy broke its official silence on the spy report, saying, “We are working with the German government to ensure this issue is resolved appropriately.” The short statement reiterated that Washington does not discuss details of alleged intelligence activity or pending law enforcement matters.