Six lawmakers have asked the State Department to investigate whether Huawei and other infrastructure vendors violated U.S. sanctions against Iran by selling telecommunications equipment to the Middle East nation.

The officials said in a newly released letter sent Dec. 22 by Rep. Sue Myric's office that media reports suggested that China-based Huawei provided the Iranian government with surveillance gear that was used to track the location of cell phones used by dissidents, who were then arrested.

The letter also cited reports that gear provided to Iran by Ericsson, Nokia Siemens Networks, Creativity Software and AdaptiveMobile Security could have been used by the government to spy on citizens.

"We ask you to expeditiously investigate whether Huawei and other telecommunications firms have violated section 106 of CISAD A by providing sensitive technology to the Iranian government that is or has been used to restrict the speech of the Iranian people and the free flow of unbiased information in Iran, and that you ensure taxpayer funds are not being used to support companies engaged in such activity," the lawmakers said in their letter.

Huawei said that the reports cited in the letter were "inaccurate."

"Unfortunately, a few members of Congress continue to cite inaccurate media reports that include groundless allegations and errors of fact," Huawei said. The company says it has "never been involved in" and does not "provide any services relating to monitoring or filtering technologies."

Iran's bloody crackdown on its citizens has prompted the United States to impose tough sanctions on the country, including a law that bars the federal government from hiring firms that provide telecommunications gear to Iran.

Huawei said on Dec. 9 that it would restrict business in Iran due to the country's "increasingly complex situation." The company also said that it has "been in full compliance with all applicable laws and regulations" from the United Nations, United States and European Union.

Huawei repeatedly has been the subject of government scrutiny because of its alleged ties to the Chinese military, claims that Huawei denies. The government's security concerns about the company have hampered its efforts to expand into the U.S. wireless market.

In addition to Myric, a Republican from North Carolina, the letter was also signed by Virginia Republican Congressman Frank Wolf and Republican Sens. Jon Kyl of Arizona, Jeff Sessions of Alabama and James Inhofe of Oklahoma. Rhode Island Democrat Sen. Sheldon Whitehouse also signed the letter.