In his first TV interview since fleeing to Russia, Snowden told German broadcaster ARD: "If there's information at Siemens that's beneficial to US national interests, even if it doesn't have anything to do with national security, then they'll take that information nevertheless."
The 30-year-old also said it was unlikely that Chancellor Angela Merkel was the only member of the German government whose phone was tapped by the NSA.
"I would say it is not very likely that someone who cares about intentions of the German government, only monitors Merkel," he said.
The former NSA contractor also spoke about how he feared for his life.
"These people, and they are government officials, have said they would love to put a bullet in my head or poison me when I come out of the supermarket, and then watch as I die in the shower," he said in the interview which was filmed in Moscow.
The comment comes just days after Snowden's Russian lawyer Anatoly Kucherena said the American feared for his life, following a report by US website BuzzFeed of explicit threats against him from unnamed Pentagon and NSA officials.
Snowden, is wanted by US authorities on treason charges for disclosing details of a vast intelligence operation that monitored millions of phone calls and emails across the world.
He received temporary asylum in Russia in August – a move that infuriated the United States and was a key factor behind President Barack Obama's decision to cancel a summit with Russia's Vladimir Putin last year.
On Thursday, in a question-and-answer session on the "Free Snowden" website, the fugitive ruled out returning to the United States, where he said there was no chance of a free trial.