Letter follows circulation of pictures on the Internet showing NSA ...

Intercepted packages are opened carefully at the NSA to implant surveillance beacons before being repackaged and sent along to unwitting global customers. (Glenn Greenwald/Nowhere to Hide)

Cisco Systems Inc's chief executive officer has written a letter to U.S. President Barack Obama urging him to curtail government surveillance after evidence circulated showing the U.S. National Security Agency had intercepted Cisco equipment, a company spokesman said on Sunday.​

In a letter dated May 15, John Chambers, chief executive officer and chairman of the networking equipment giant, warned of an erosion of confidence in the U.S. technology industry and called for new "standards of conduct" in how the NSA conducts its surveillance.

• Glenn Greenwald says NSA bugs tech hardware en route to global cust...

• NSA document raises questions about Canada in G8 spying

• Edward Snowden appears via video at Toronto debate

• Munk Debate on surveillance: Glenn Greenwald, Michael Hayden trade ...