The Chinese government appears to be abiding by its September pledge to stop supporting the hacking of American trade secrets to help companies there compete, private U.S. security executives and government advisers said on Monday.

FireEye Inc, the U.S. network security company best known for fighting sophisticated Chinese hacking, said in a report released late Monday that breaches attributed to China-based groups had plunged by 90 percent in the past two years. The most dramatic drop came during last summer's run-up to the bilateral agreement, it added.

FireEye's Mandiant unit in 2013 famously blamed a specific unit of China's Peoples Liberation Army for a major campaign of economic espionage.