New claims that the US may have spied on German Chancellor Angela Merkel's mobile phone for more than 10 years have been published by a German magazine.
Citing secret documents, Der Spiegel said Mrs Merkel's number was on a National Security Agency (NSA) list dating from 2002 - before she became chancellor - and was still on a surveillance list weeks before US President Barack Obama visited Germany in June.
The nature of the monitoring of Mrs Merkel's mobile phone is not clear from the files, the magazine says.
For example, it is possible that the chancellor's conversations were recorded, or that her contacts were simply assessed.
The BBC reports Germany is sending its top intelligence chiefs to Washington in the coming week to "push forward" an investigation into the spying allegations, which have caused outrage in Germany.
The documents seen by Der Spiegel give further details of the NSA's targeting of European governments.
A unit called Special Collection Services, based in the US embassy in Pariser Platz in Berlin, was responsible for monitoring communications in the German capital's government quarter.
If the existence of listening stations in US embassies were known, there would be "severe damage for the US's relations with a foreign government," the documents said.
Similar units were based in around 80 locations worldwide, according to the documents seen by the magazine, 19 of them in European cities.
In Washington, meanwhile, hundreds of protesters marched to the US Capitol on Saturday to demand a limit to the surveillance.
Some held banners in support of the fugitive former contractor Edward Snowden, who revealed the extent of the NSA's activities.
Estimates varied on the size of the march, with organizers saying more than 2000 attended, Reuters reports. US Capitol Police said they do not typically provide estimates on the size of demonstrations.
The march attracted protesters from both ends of the political spectrum as liberal privacy advocates walked alongside members of the conservative Tea Party movement in opposition to what they say is unlawful government spying on Americans.