WASHINGTON: The Federal Communications Commission on Tuesday formally designated Chinese's Huawei Technologies Co and ZTE Corp as posing threats to US national security, a declaration that bars US firms from tapping an $8.3 billion government fund to purchase equipment from the companies.

The US telecommunications regulator voted in November 5-0 to issue the declaration and proposed requiring rural carriers to remove and replace equipment from the two Chinese companies from existing US networks.

"We cannot and will not allow the Chinese Communist Party to exploit network vulnerabilities and compromise our critical communications infrastructure," FCC Chairman Ajit Pai said in a statement Tuesday.