The UK government and National Cyber Security Centre (NCSC) told mobile operators to carefully consider their choices of 5G equipment suppliers, ahead of the publication of a review into the security of the country’s telecoms infrastructure, Financial Times (FT) reported.

Their warning came in a letter sent to operators co-signed by NCSC CEO Ciaran Martin and Matthew Gould, director general of Digital and Media policy in the Department of Digital, Culture, Media and Sport.

FT reported the letter told service providers 5G supply chains could be impacted by the outcome of the review, as new regulations related to infrastructure procurement might be imposed.

The review was launched in July and aims to assess the security and resilience of the UK’s telecoms network ahead of 5G rollouts. No date for the publication of conclusions has been confirmed.

Earlier this year, the NCSC branded the use of equipment from ZTE a security threat and in July voiced concerns about the resilience of kit from Huawei. Later that month Huawei vowed to address security concerns in the country and has since partnered with EE on a 5G trial in London.

Although several of FT’s sources speculated the letter was a warning on the exclusive use of Huawei infrastructure, a government representative denied this was the case.

Scrutiny from security chiefs comes as other countries, led by the US, assess perceived security risks associated with infrastructure supplied by Chinese vendors and, in the case of the US and Australia, took action to push ZTE and Huawei out of the race to supply 5G infrastructure.