Germany has arrested an employee of the German Federal Intelligence Agency (BND) for alleged spying on behalf of the United States, the German Federal Prosecutor's office said.

The 31-year-old man allegedly has admitted passing on information to a U.S. contact about a special parliamentary committee investigating Edward Snowden's revelations about U.S. National Security Agency spying, Reuters reported.

Reuters quoted two politicians with knowledge of the situation as saying the suspect "had no direct contact with the investigative committee" and had offered his services to the United States voluntarily.

There was no comment from German Chancellor Angela Merkel, the White House or the U.S. State Department. Merkel and President Barack Obama spoke Thursday, but a White House readout of the conversation did not indicate whether the spying issue was addressed.

The German Foreign Ministry Friday issued a statement saying U.S. Ambassador John B. Emerson has been summoned and "asked to help in the swift clarification" of the case, the Associated Press reported.

Bild newspaper reported the suspect had been working as a double agent for two years and had stolen 218 confidential documents, allegedly accepting 25,000 euros ($34,100). Der Spiegel said he worked in the mailroom.

Deutsche Pressse Argentur reported there would be a major diplomatic crisis if the charges are proved. The United States and Germany regularly swap intelligence, but Snowden's revelations, which included indications the NSA had monitored Merkel's mobile phone, have strained relations.

DPA said the suspect was a mid-level clerk who was arrested initially on suspicions of spying for Russia.