A former National Security Agency (NSA) chief who was in the post when the Edward Snowden scandal broke has joined Amazon's board as a director.
Gen Keith Alexander, whose appointment was made public on Wednesday, became known to the public after Mr Snowden blew the whistle on the agency's mass surveillance programs.
A spokesman for Privacy International told the BBC the move was "worrying".
The BBC has asked Amazon for comment.
Hours after Gen Alexander's appointment was made public Mr Snowden took to Twitter to voice his concern.
"It turns out 'Hey Alexa' is short for 'Hey Keith Alexander,'" he tweeted.
"Yes, the Keith Alexander personally responsible for the unlawful mass surveillance programs that caused a global scandal," he added.
Last week, a US federal court ruled that the NSA's phone record surveillance, uncovered by Mr Snowden in 2013, was illegal.
Gen Alexander suggested at the time that reporters should not have been allowed to report on the documents that were leaked by Mr Snowden.
“I think it’s wrong that that newspaper reporters have all these documents, the 50,000-whatever they have and are selling them and giving them out as if these - you know it just doesn’t make sense,” he told the Verge in 2013.
“We ought to come up with a way of stopping it," he added.
'We don't need another NSA'
Edin Omanovic, advocacy director at Privacy International, said Amazon's decision to hire Gen Alexander was deeply concerning.
"Every day, big tech companies like Amazon make huge ethical decisions which affect people’s lives without any democratic accountability," he said.
Mr Omanovic suggested the move could make it easier for Amazon to exercise its influence in the security market.
"Amazon now wants to corner in on the lucrative defence and security market - and with that the keys to the huge data stores held by governments.
"It is no secret that the key to this is hiring influential former public servants. The concentration of power that will arise from this is bad for people, bad for companies, and bad for societies," he added.
Last year, it emerged that Amazon's Alexa was among a variety of smart voice assistants that had been sending voice recordings to human contractors for review.
Amazon has since made it possible for consumers to opt-out of such reviews.