Berlin: Germany's top prosecutor dropped a probe into the alleged tapping of Chancellor Angela Merkel's mobile phone by US spy services, citing a lack of evidence.

Investigators interviewed security officials and found no clear proof that the US listened to Mrs Merkel's phone conversations, the Federal Prosecutor General's office said in a statement on Friday. Steffen Seibert, the chancellor's chief spokesman, declined to comment on the decision when asked by reporters in Berlin.

German Chancellor Angela Merkel holds a BlackBerry mobile device at a trade fair in 2013. A probe into the alleged tapping of her phone by US intelligence agencies has been dropped. Credit:JULIAN STRATENSCHULTE

The allegations caused a political stir in Germany in 2013 when news magazine Der Spiegel reported that US intelligence may have been monitoring Mrs Merkel's private mobile phone for years. Mrs Merkel promptly complained to President Barack Obama about the alleged spying, and received assurances from him that the US was not listening to her calls.

Mrs Merkel's efforts since then to win US assurances to limit spying in Germany have gone nowhere. Her talks with US officials have been hampered by reports that the country's BND intelligence agency collaborated with the NSA to spy on European allies and companies. The dispute has dragged on for two years, with the spat leading to the departure last year of the top US intelligence officer in Berlin.

Investigators were unable to get their hands on a National Security Agency document cited by former NSA contractor Edward Snowden as proof of the spying, the prosecutor's office said.

Prosecutors said they're still looking into possible US mass spying on Germans and will restart the Merkel phone-tapping investigation if they find new leads.

Bloomberg