BERLIN — Germany summoned the U.S. ambassador in Berlin on Friday after the arrest of a man reported to have spied for the United States, heightening friction between the two countries over suspected U.S. eavesdropping in Germany.

U.S. Ambassador John Emerson was summoned “in connection with an investigation by the federal prosecutor,” the German Foreign Ministry said in a statement. The U.S. envoy “was asked to help in the swift clarification” of the case, it added.

Federal prosecutors say a 31-year-old German was arrested Wednesday on suspicion of spying for foreign intelligence services. They did not identify the suspect or the intelligence services.

German government spokesman Steffen Seibert said Chancellor Angela Merkel had been personally informed of the arrest.

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He declined to comment on reports by Der Spiegel magazine and the daily Sueddeutsche Zeitung that the man worked for Germany’s foreign intelligence service, known by its German initials BND.

The newspapers, which didn’t identify their sources, said the man was suspected of passing on information about a German parliamentary committee investigating the activities of U.S. and other intelligence agencies in Germany. He claimed to have worked with U.S. intelligence since 2012, they reported.

Seibert said members of the parliamentary panel had also been informed of the arrest.

Reports that the National Security Agency (NSA) spied on German citizens, including eavesdropping on Merkel’s cellphone calls, have caused friction between Germany and the U.S. since they were published last year, based on documents leaked by former NSA contract worker Edward Snowden.

Martina Renner, a member of the opposition Left Party on the parliamentary panel, said the case indicated that anyone who examined Snowden’s revelations in detail was subject to scrutiny by U.S. intelligence agencies.

The panel heard its first testimony Thursday from two Americans who formerly worked for the NSA, Thomas Drake and William Binney.

“If the media reports (about the case) are confirmed, then there can’t just be a legal response, there also has to be a political response,” she said.

In his testimony, Drake claimed that cooperation between the NSA and Germany’s BND greatly increased after the 9/11 terrorist attacks in the United States. He described the German spy agency as an “appendage” of the NSA.

Seibert said Merkel discussed “foreign-policy matters” in a telephone conversation with President Obama late Thursday. He said the conversation focused on Ukraine but wouldn’t say whether the arrest was also discussed.

The U.S. National Security Council declined to comment Friday, and BND didn’t immediately return a call seeking comment.