Democratic candidates for political office have reportedly been warned by their party to avoid using mobile devices from Chinese telecom companies ZTE Corporation and Huawei Technologies, as a preventative measure against possible electronic espionage.

Citing a Democratic source, Reuters reported last Friday that Bob Lord, the Democratic National Committee's chief security officer, sent an email to candidates stating: "Please make sure that you are not using or purchasing ZTE or Huawei devices anywhere within your staff -- for personal or work-related use."

Despite a lack of publicly shared evidence, concerns have mounted within the U.S. intelligence community and some members of Congress that ZTE and Huawei products could be leveraged by the Chinese government to spy on American targets.

Last February, six top U.S. intelligence officials provided testimony to the Senate Intelligence Committee in which they advised against government bodies or private citizens using equipment or services from the two China-based firms, due to cyber espionage risks. The Department of Defense has already banned the sale of Huawei and ZTE phones on U.S. military bases.

Additionally, on Aug. 1, Congress passed its annual defense spending bill, which this year contained language prohibiting the DOD and its contractors from  procuring equipment from ZTE and Huawei. Stronger measures suggested by the Senate that would have effectively banned ZTE from U.S. operations did not make the final cut.

The U.S. had recently imposed a U.S. trade ban on ZTE products for allegedly violating sanctions on Iran and North Korea. But  in June the Department of Commerce, under the Trump administration, agreed to lift the ban after only three months, in exchange for the company paying a $1.4 billion financial penalty. The deal was consummated over the strenuous objections of certain lawmakers on both sides of the aisle, who said ZTE constitutes a national security threat.