BERLIN - US President Barack Obama was personally informed of mobile phone tapping against German Chancellor Angela Merkel, which may have begun as early as 2002, German media reported Sunday as a damaging espionage scandal widened.
Bild am Sonntag newspaper quoted US intelligence sources as saying that National Security Agency chief Keith Alexander had briefed Obama on the operation against Merkel in 2010.
"Obama did not halt the operation but rather let it continue," the newspaper quoted a high-ranking NSA official as saying.
News weekly Der Spiegel reported that leaked NSA documents showed that Merkel's phone had appeared on a list of spying targets since 2002, and was still under surveillance shortly before Obama visited Berlin in June.
As a sense of betrayal spread in many world capitals allegedly targeted by the NSA, the spying row prompted European leaders late last week to demand a new deal with Washington on intelligence gathering that would maintain an essential alliance while keeping the fight against terrorism on track.
Germany will send its own spy chiefs to Washington soon to demand answers.
Meanwhile, several thousand protesters gathered in Washington on Saturday to call for new US legislation to curb the NSA's activities and improve privacy.
Merkel confronted Obama with the snooping allegations in a phone call on Wednesday saying that such spying would be a "breach of trust" between international partners.
The suspicion also prompted Berlin to summon the US ambassador - a highly unusual move between the close allies.
The Frankfurter Allgemeine Sonntagszeitung reported that Obama had told Merkel during their call that he had been unaware of any spying against her. It did not cite its sources.
Der Spiegel said he told her that if he had been informed of the operation he would have stopped it at once.