ZTE reported a net loss of 1.945 billion yuan ($311.43 million) for the three months ended September 30 compared with a net profit of 299.27 million yuan in the same period last year.
Revenue fell 13 percent to 18.09 billion yuan from 20.83 billion yuan a year earlier.
ZTE released a profits warning earlier this month, saying it expected a net loss of between 1.9 billion and 2.0 billion yuan for the third quarter.
The company earlier this month announced that US network giant Cisco Systems had ended a 2005 strategic cooperation agreement, after the Chinese firm was accused by US lawmakers of doing business with Iran and posing a security threat.
A US congressional investigation said ZTE and another Chinese telecom firm, Huawei, should be barred from US contracts and acquisitions.
The report by the House Intelligence Committee said the two firms "cannot be trusted" to be free of influence from Beijing and could be used to undermine US security.
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