WASHINGTON - The imbroglio over the tapping of Angela Merkel's phone deepened on Sunday, after a US denial that President Barack Obama was personally informed for years of electronic surveillance against the German chancellor.
As a sense of betrayal spread in European capitals about spying activities conducted against world leaders and ordinary citizens, German media reports said tapping of Dr Merkel's phone may have begun as early as 2002.
Bild am Sonntag newspaper quoted US intelligence sources as saying that America's National Security Agency chief General Keith Alexander had briefed Mr Obama on the operation against Dr 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 Dr Merkel's phone had appeared on a list of spying targets for over a decade, and was still under surveillance weeks before Obama visited Berlin in June.
But NSA spokesman Vanee' Vines, in Washington, flatly denied the claims.
Gen Alexander "did not discuss with President Obama in 2010 an alleged foreign intelligence operation involving German Chancellor Merkel, nor has he ever discussed alleged operations involving Chancellor Merkel," Ms Vines said.
"News reports claiming otherwise are not true," she added.
The allegations, derived from documents acquired from US fugitive defence contractor Edward Snowden, have stoked global outrage that American spy agencies were responsible for broad snooping into the communications of several dozen world leaders and likely millions of ordinary people.