The U.S. Justice Department has joined two other agencies probing Huawei Technologies Co. for possible violations of sanctions banning sales to Iran, according to two people familiar with the matter. Agents from the Federal Bureau of Investigation, which is overseen by the Justice Department, have been looking into transactions by the Shenzhen, China-based mobile and telecommunications giant, the people said. According to one of them, the criminal inquiry grew out of an earlier sanctions-violation probe that ultimately led to penalties against another Chinese technology company, ZTE Corp. The U.S. Treasury Department\u2019s Office of Foreign Assets Control, or OFAC, which enforces sanctions, and the Department of Commerce are also looking into Huawei\u2019s transactions. The Commerce Department in 2016 issued an administrative subpoena aimed at Huawei, China\u2019s largest maker of telecommunications equipment, seeking information about whether it was sending U.S. technology to rogue nations including Syria, Iran and North Korea. Earlier this month, the Commerce Department banned ZTE, China\u2019s second-biggest network equipment maker, from buying U.S.-made components as punishment for violating a sanctions settlement over transactions with Iran and North Korea. ZTE had previously reached a settlement with the Commerce Department\u2019s Bureau of Industry and Security, and pleaded guilty as part of a sanctions-violations agreement with the Justice Department. ZTE agreed to pay $892 million in fines and forfeitures in the Justice Department deal, at the time the largest U.S. criminal fine against a Chinese company, with additional fines if it failed to comply with the deal. Rival \u2018F7\u2019 Internal ZTE documents posted on the Commerce Department website cited a rival, referred to only as \u201cF7,\u201d as also violating U.S. export controls in sales of equipment to Iran. A group of Republican lawmakers pushed the Trump administration last April to investigate and identify F7, citing news reports that have highlighted the similarities between the company described in the documents and Huawei. The FBI and OFAC investigations into Huawei have been going on since at least early 2017, according to one of the people with knowledge of the probes, who asked not to be identified because he isn\u2019t authorized to speak about the matter. A finding of wrongdoing by Huawei and a similar U.S. supplier export ban "would have wide ramifications on various suppliers on a larger scale than peer ZTE, in our view," according to Bloomberg Intelligence technology analysts Woo Jin Ho and Anand Srinivasan. "Chip suppliers such as Skyworks and Qorvo, each with about 10 percent sales exposure to Huawei, would be affected. Optical suppliers including NeoPhotonics, Oclaro and Lumentum may also be exposed." Some Huawei suppliers in Asia slid after the news, with Chinasoft International Ltd. tumbling as much as 21 percent and Sunny Optical Technology Group Co. fell 7.4 percent. Huawei Technologies\u2019 $500 million of 2027 notes fell 0.9 cents on the dollar to a record low of 93.2 cents in Hong Kong trading. Its bonds are the worst performers in the Bloomberg Barclays Asia dollar bond index Thursday. \u2018Actively Cooperates\u2019 Glenn Schloss, a spokesman for Huawei in Shenzhen, declined to comment about the probes. The company has said it complies with all applicable laws and regulations where it operates, including U.S. export controls and sanctions laws and regulations, and that it \u201cactively cooperates\u201d with government agencies regarding its compliance. A spokesman for the Justice Department declined to comment. Separately, the U.S. Federal Communications Commission voted unanimously last week to ban federal funds from being used to purchase networking gear from companies determined to be a national security risk, dealing another blow to ZTE and Huawei. The measure has yet to be finalized. FCC Chairman Ajit Pai cited the risk of \u201chidden \u2018back doors\u2019 to our networks in routers, switches and other equipment\u201d that could \u201callow hostile foreign powers to inject viruses and other malware.\u201d No Threat Schloss, the Huawei spokesman, said those allegations aren\u2019t true. \u201cWe pose no security threat in any country,\u201d he said. \u201cU.S. authorities should not base government decisions on speculation or rumor. In 30 years, not a single operator has experienced a security issue with our equipment.\u201d Huawei was founded in 1988 by former Chinese army engineer Ren Zhengfei, leading to congressional concerns over Chinese military and government influence at the company. In addition to producing networking gear and other electronics, it was the globe\u2019s No. 3 smartphone seller last year behind Samsung Electronics Co. and Apple Inc. Huawei has faced several setbacks in the U.S. this year. AT&T Inc. and Verizon Communications Inc., the biggest U.S. carriers, dropped plans to sell Huawei\u2019s latest smartphones. Then, consumer electronics retailer Best Buy Co. stopped selling Huawei phones, laptops and smartwatches. Earlier Wednesday, the company dropped a planned dollar-denominated bond sale and delayed pricing a European offering. Huawei maintains research and development facilities in Texas, New Jersey, California and four other U.S. states, all of which provide technology for Huawei\u2019s global operations. Despite the setbacks, Huawei said last month that 2017 net income rose 28 percent and that growth in markets from the Middle East to Africa have it targeting record sales of $102.2 billion this year.