China's Huawei Technologies and ZTE Corp, currently two of the leading global telecommunication firms, have informed the U.S. Congress on Thursday that they were not willing tools at the disposal of Beijing to spy on other nations.

The companies sent their two top executives to appear before the underway U.S. legislative probe that seeks to shed light on allegations that both Huawei ZTE pose risks to the United States' economic interests.

A committee report that will be released by U.S. lawmaker Mike Rogers will play a crucial role in determining if Huawei and ZTE will be allowed to expand their operations in America.

It is alleged that equipments marketed by the two firms allow China to spy on countries where they operate but company executives told the U.S. legislators that their businesses function outside of Beijing's influence.

In his testimony, Huawei senior vice president Charles Ding rejected suggestions that his company, based in Shenzhen, China, partly exists to serve the dictates and interests of the Chinese government.

"Huawei has not and will not jeopardize our global commercial success nor the integrity of our customers' networks for any third party, government or otherwise," Mr Ding was reported by Reuters as saying on Thursday.

His ZTE counterpart, Zhu Jinyun, addressed Mr Roger's concerns on reports "about backdoors or unexplained beaconing from the equipment sold by both companies."

Those concerns, according to Mr Zhu, were software bugs that will go away through normal updates, which he noted were the standard procedures that were also in play on companies like Apple, Google and Microsoft.

The ongoing investigation is in response to earlier reports by U.S. intelligence agencies that China is actively engage in economic espionage, with giant Chinese firms likely acting as gateways to purported breaches in the past.

The same concern was reportedly raised by Australia's intelligence officials in advising Attorney-General Nicola Roxon to block Huawei from participating in the $36 billion roll out of the national broadband network (NBN).

Huawei criticised the decision as both unfair and unproductive but Prime Minister Julia Gillard defended move and insisted that she was protecting Australia's national interest, which Beijing should understand.

Mr Ding, for his, part had reiterated that the security concerns "non-specific and unsubstantiated."

To prove that Huawei and ZTE were conducting their business operations in good faith, the two executives had agreed to furnish Mr Rogers a list of company officials that are in the Communist Party roll.

The committee chair said the initiative should at least erase suspicions considering that Huawei's founder was formerly a ranking intelligence official of the Chinese military organisation.

Mr Rogers told Reuters that so far the inquiry has been getting "poor response," from Huawei and ZTE officials but he vowed to put out "a fair and accurate final report."