The decision came in April after the utility sought advice from the National Cyber Security Center (NCSC), a branch of the nation's signals intelligence agency, Government Communications Headquarters (GCHQ), the newspaper quoted a Whitehall official as saying.
National Grid declined to comment citing "confidential contractual matters." "We take the security of our infrastructure very seriously and have effective controls in place to protect our employees and critical assets to ensure we can continue to reliably, safely and securely transmit electricity," it said in a statement.
The report said an employee at the Nari subsidiary, NR Electric Company-U.K., had said the company no longer had access to sites where the components were installed, and that National Grid did not disclose a reason for terminating the contracts.
It quoted another person it did not name as saying the decision was based on NR Electric Company-U.K.'s components that help control and balance the grid and minimize the risk of blackouts.
It was unclear whether the components remained in the electricity transmission network, the report said.
NR Electric Company-U.K., GCHQ and the Chinese Embassy in London did not immediately respond to requests for comment outside of business hours.
Britain's Department for Energy Security and Net Zero said that it did not comment on the individual business decisions taken by private organizations. "As a government department we work closely with the private sector to safeguard our national security," it said in a statement.