Snowden, a former NSA contractor said this in an interview to German public television broadcaster ARD broadcast last night.
"There is no doubt that the NSA is involved in economic espionage," Snowden said in his first tv interview since he fled to Moscow via Hong Kong in June.
The 30-year-old was granted a one-year asylum by the Russian authorities in August.
"If there is information at Siemens that they (the NSA) think would be beneficial for the national interests, not the national security of the United States, they will go after that information and get it," he said.
In a statement published by the paper, a NSA spokesperson said "we do not use foreign intelligence capabilities to steal the trade secrets of foreign companies on behalf of - or give intelligence we collect to - US companies to enhance their international competitiveness or increase their bottom line."
The latest allegations that the US spied on big German companies competing with US industries are bound to aggravate a conflict between the two countries, triggered by Snowden's disclosures last year that the NSA also allegedly spied on Angela Merkel's mobile phone for several years.
It also has been pressing the US for the signing of a bilateral "no spy agreement".
In the interview, Snowden also alleged that he was getting life threats from American officials, who he said wanted to assassinate him.
He referred to an article published by the BuzzFeed website, which quoted unnamed Pentagon and NSA officials.
"These people -- and they are government officials- have said that they would love to fire a bullet into my head or poison me when I return from the supermarket and to watch me die in the shower," he told the network.
