The National Cyber Security Centre (NCSC), which is the UK’s cyber defense watchdog, has written to UK telecoms providers warning them that the use of ZTE’s equipment and services within the UK telecommunications infrastructure environment could pose a national security risk.

ZTE is a Chinese state-owned enterprise.

“It is entirely appropriate and part of NCSC’s duty to highlight potential risks to the UK’s national security and provide advice based on our technical expertise,” NCSC technical director Ian Levy said in a letter sent to UK telcos, the regulator Ofcom and ZTE.

“NCSC assess that the national security risks arising from the use of ZTE equipment or services within the context of the existing UK telecommunications infrastructure cannot be mitigated,” he added.

The US government has also prohibited American telecoms firms from buying network equipment from Chinese firm Huawei, and last month warned US citizens not to use smartphones from the Chinese companies Huawei and ZTE.