US intelligence spied on former German chancellor Gerhard Schroeder from 2002, NDR television and the Sueddeutsche Zeitung daily reported Tuesday, adding fuel to the flames of a row over spying on incumbent Angela Merkel.

US intelligence spied on former German chancellor Gerhard Schroeder from 2002, NDR television and the Sueddeutsche Zeitung daily reported Tuesday, adding fuel to the flames of a row over spying on incumbent Angela Merkel.

Schroeder, the Social Democrat chancellor who served from 1998 to 2005, appears on a list of names of people and institutions put under surveillance by the US National Security Agency (NSA) from 2002, at the start of his second mandate as German head of state.

At the time Germany was opposing intervention in Iraq.

US-German ties soured amid revelations leaked by former CIA contractor Edward Snowden that US intelligence agencies had eavesdropped on Merkel and collected vast amounts of online data and telephone records from average citizens.

The dispute has threatened to derail negotiations on a sweeping transatlantic free trade agreement known as TTIP.

US President Barack Obama in a recent interview assured that Merkel was no longer under surveillance.

His Secretary of State John Kerry acknowledged Friday that relations with Germany had gone through a "rough period" over the NSA snooping but said that shared interests would help put ties back on track.

Kerry, speaking in Berlin, said then that the United States took Germany's anger over revelations that US intelligence monitored Merkel's mobile phone seriously.