A Chinese telco banned by successive federal governments from being used by the NBN over security concerns has had its phones approved for use by Defence officials and top diplomats.

Huawei was founded by former People's Liberation Army engineer Ren Zhengfei and its equipment was banned from being used on the NBN, in part on advice from Australia's intelligence agencies, in 2013.

A Chinese firm banned from working on the NBN over security concerns has been approved to supply phones to Defence. Credit:Andrew Quilty

That decision was made despite the firm signing up influential Coalition and Labor figures, including Alexander Downer and John Brumby, and over the objections from some in the Coalition, including then shadow communications spokesman Malcolm Turnbull.

In addition to the domestic security concerns raised about Huawei, a 2012 US Congressional investigation highlighted the firm's links to the Chinese government and concluded that "based on available classified and unclassified information, Huawei and ZTE cannot be trusted to be free of foreign state influence and thus pose a security threat to the United States and to our systems".