By SIOBHAN GORMAN
Updated June 13, 2012, 12:21 p.m. ET
WASHINGTON—Lawmakers investigating spying threats from China are pressing two Chinese telecommunications firms active in U.S. markets for details about their relationship with the Chinese government and with U.S. companies.
In letters sent Tuesday to Huawei Technologies Co. and ZTE Corp., the top lawmakers on the House intelligence committee outlined concerns about the companies' ties with the Chinese government, including the role of a "party committee" at Huawei.
The lawmakers also asked about Huawei's relationships with five U.S. consulting firms and requested an expansive collection of documents, including the contracts between the firms and Huawei as well as the results of the firms' consulting work for Huawei. Those firms include International Business Machines Corp., Accenture PLC and PricewaterhouseCoopers LLP.
Additional questions address work the two companies have done in Iran and their funding arrangements with the Chinese government.
The requests, from Reps. Mike Rogers (R., Mich.) and C.A. Dutch Ruppersberger (D., Md.), provide an initial review of topics under investigation by the committee, which launched a probe late last year into possible threats posed to U.S. national security by Chinese telecommunications firms seeking to do business in the U.S.
"We're very concerned about the Chinese government hacking our national networks," Mr. Ruppersberger said.
The probe, which is ongoing, reflects growing U.S. fears that the Chinese government could access Huawei or ZTE telecommunications equipment and track phone calls or emails, or disrupt or destroy a communications system.
Huawei is a rapidly growing, closely held firm that has sold telecom equipment—including landline, wireless and radio networks—to more than a dozen small U.S. carriers in rural areas as well as metro areas like Chicago. It also makes tablets and smartphones.
ZTE, a maker of telecommunications equipment that derives about half its sales from overseas, has indicated an interest in growing its U.S. presence. Like Huawei, its U.S. headquarters is in Texas and it has hired lobbyists in Washington, D.C.
The companies have stated that their interaction with the Chinese government is typical of a regulated company in China.
At Huawei, spokesman Bill Plummer said the company is just beginning to review the lawmakers' questions and welcomes the opportunity to provide the committee with facts.
Following the investigation, Mr. Plummer said, "we look forward to refocused attention to addressing the true threats to critical infrastructure."
ZTE spokesman Mitchell Peterson said, "as recognized by the committee, ZTE is committed to 'remaining transparent, candid, and cooperative' throughout this inquiry." A Chinese embassy spokesman declined to comment.
A PricewaterhouseCoopers spokesman said the company cannot comment on its clients. A spokesman for IBM declined to comment, while Accenture didn't immediately respond to requests for comment.
The lawmakers don't directly address the potential use of Huawei or ZTE telecommunications products to provide a backdoor for Chinese spying, but the committee continues to examine such concerns, a committee aide said.
Mr. Rogers said he is concerned that these Chinese firms provide opportunities for foreign and economic espionage. He said while he appreciates the companies' cooperation, "their answers to our questions have yet to be persuasive."
He said he remains "deeply concerned about the risk posed to our critical telecommunications infrastructure were these companies to have further access to the U.S. market."
The letters follow up on a series of recent meetings in China between lawmakers and committee staff and representatives from each company. Huawei representatives met with committee staff for 11 hours, and ZTE met with committee aides for about five hours, a committee aide said. Lawmakers followed up with additional meetings in Hong Kong last month with top executives from both companies.
The questions highlight lawmakers' concerns about a Chinese law that allows the government to task Chinese companies with providing information or acting on behalf of the government. The questions also delve into the complicated details of preferential financing the companies may have received from the Chinese government.
In its extensive request for Huawei, the committee asks for details of any connection to a range of government ministries and for further explanation of the role of the company's "party committee," including its powers and who is on it.
The committee also requested details of ZTE's U.S. operations, noting that it got mixed signals from different company officials. Some said the company didn't present a security threat to the U.S. because it had such a small footprint, while others said the company is willing to lose money to gain a larger foothold in U.S. markets.