SAN FRANCISCO, May 20 (Xinhua) -- Amazon is under mounting pressure from civil rights groups to stop sale of facial recognition technology to government as U.S. rights advocacy leader the American Civil Liberties Union (ACLU) Monday urged Amazon investors to vote against it.

In an open letter to Amazon shareholders, the ACLU urged the tech giant's investors to use their power to stop Amazon's deployment of its invasive face surveillance technology, Rekognition.

"Your vote on these proposals will help chart the course for the kind of society we'll have to live in, and whether that society will be forced to suffer under continuous, inescapable, and dangerous government surveillance," the ACLU said.

The union's open letter came two days before an Amazon investors' meeting to be held on Wednesday.

The ACLU said the face surveillance technology fundamentally changes the balance of power between government and individuals, which gives governments "unprecedented power to track, control and harm people."

"Without shareholder action, Amazon may soon become known more for its role in facilitating pervasive government surveillance than for its consumer retail operations," it said.

It encouraged Amazon shareholders to stand out against the company's plan to sell facial recognition technology to government agencies by citing the example of San Francisco that has decided to ban the use of such technology by government departments.

On Tuesday, San Francisco became the first U.S. major city to voted 8-1 in favor of an ordinance barring the police department and other city agencies from using facial recognition technology on residents.

Other U.S. cities are also considering similar bans, including California's Oakland and Somerville city in Massachusetts.