US prosecutors in New York have been investigating whether Chinese tech company Huawei violated US sanctions in relation to Iran, according to sources familiar with the situation.

Since at least 2016, US authorities have been probing Huawei’s alleged shipping of US-origin products to Iran and other countries in violation of US export and sanctions laws, two sources said.

News of the Justice Department probe follows a series of US actions aimed at stopping or reducing access by Huawei and Chinese smartphone maker ZTE Corp to the US economy amid allegations the companies could be using their technology to spy on Americans, Reuters reported.

The Justice Department probe is being run out of the US attorney’s office in Brooklyn, the sources said. John Marzulli, a spokesman for the prosecutor’s office, would neither confirm nor deny the investigation. The probe was first reported by the Wall Street Journal on Wednesday.

Huawei, the world’s largest maker of telecommunications network equipment and the No. 3 smartphone supplier, said it complies with “all applicable laws and regulations where it operates, including the applicable export control and sanction laws and regulations of the UN, US and EU.”

The probe of Huawei is similar to one that China’s ZTE Corp says is now threatening its survival. The United States last week banned American firms from selling parts and software to ZTE for seven years.

Washington accused ZTE of violating an agreement on punishing employees after the company illegally shipped US goods to Iran.

ZTE, which sells smartphones in the United States, paid $890 million in fines and penalties, with an additional penalty of $300 million that could be imposed.

US authorities have subpoenaed Huawei seeking information related to possible export and sanctions violations. The New York Times last April reported the US Treasury’s Office of Foreign Assets Control subpoena, issued in December 2016, following a Commerce Department subpoena that summer.

Both companies also have been under scrutiny by US lawmakers over cybersecurity concerns.

In Beijing, foreign ministry spokeswoman, Hua Chunying, said China opposed countries imposing their own laws on others, when asked whether Huawei violated US sanctions related to Iran.

“China’s position opposing nations using their own domestic laws to impose unilateral sanctions is consistent and clear,” she told a daily news briefing.

“We hope that the United States will not take actions that further harm investors’ mood towards the business situation there.”

In February, Senator Richard Burr, the Republican chairman of the US Senate Intelligence Committee, cited concerns about the spread of Chinese technologies in the United States, which he called “counterintelligence and information security risks that come prepackaged with the goods and services of certain overseas vendors”.

Huawei and ZTE have denied these allegations.

Republican Senators Marco Rubio and Tom Cotton have introduced legislation that would block the US government from buying or leasing telecommunications equipment from Huawei or ZTE, citing concern that the Chinese companies would use their access to spy on US officials.

In 2016, the Commerce Department made documents public that showed ZTE’s misconduct and also revealed how a second company, identified only as F7, had successfully evaded US export controls.

In a 2016 letter to the Commerce Department, 10 US lawmakers said F7 was believed to be Huawei, citing media reports.

In April 2017, lawmakers sent another letter to Commerce Secretary Wilbur Ross, asking for F7 to be publicly identified and fully investigated.

The US government’s investigation into sanctions violations by ZTE followed reports by Reuters in 2012 that the company had signed contracts to ship millions of dollars’ worth of hardware and software from some of the best known US technology companies to Iran’s largest telecoms carrier.

Reuters also previously reported on suspicious activities related to Huawei. In January 2013, Reuters reported that a Hong Kong-based firm that attempted to sell embargoed Hewlett-Packard computer equipment to Iran’s largest mobile-phone operator has much closer ties to China’s Huawei Technologies than was previously known.