China's government called on Washington on Tuesday to 'stop the unreasonable crackdown' on Huawei following the tech giant's indictment in the US on charges of stealing technology and violating sanctions on Iran.

Beijing will 'firmly defend' its companies, the foreign ministry said in a statement read on state-run TV news. It gave no indication whether Beijing might retaliate for the charges against Huawei, China's first global tech brand and the biggest maker of network switching gear used by phone and internet companies.

Huawei Technologies Ltd denied committing any of the violations cited in Monday's indictment, the most serious escalation yet of pressure on Huawei, which has spent a decade battling US accusations it is a front for Chinese spying and a security risk.

The foreign ministry complained Washington has 'mobilised state power' to hurt Chinese companies 'in an attempt to strangle fair and just operations' for political reasons.

'We strongly urge the United States to stop the unreasonable crackdown on Chinese companies including Huawei,' the ministry statement said. It said Beijing will defend the 'lawful rights and interests of Chinese companies' but gave no details.

The charges unsealed on Monday accused Huawei of trying to take a piece of a robot and steal other technology from a T-Mobile lab that was used to test smartphones.

Huawei also is charged with using a Hong Kong front company, Skycom, to trade with Iran in violation of US trade controls. Prosecutors allege the company's chief financial officer, Meng Wanzhou, lied to banks about those dealings.

Meng, the daughter of Huawei founder Ren Zhengfei, was arrested on December 1 in Vancouver on US charges related to Iran, a development that set off a political firestorm between China and Canada.

'The company denies that it or its subsidiary or affiliate have committed any of the asserted violations of U.S. law set forth in each of the indictments,' a Huawei statement said. Huawei is 'not aware of any wrongdoing by Ms. Meng, and believes the US courts will ultimately reach the same conclusion,' it said.

There was no allegation Huawei was working at the Chinese government's direction. The US government previously has accused Beijing of involvement in cyberspying and theft of industrial secrets. It has charged several Chinese hackers and intelligence officials.

Huawei said US prosecutors rejected a request to discuss the investigation following Meng's arrest. It also noted the allegations in the trade secrets charge were the subject of a US civil lawsuit that already has been settled.

Meng is out on bail in Vancouver and is due in court on Tuesday as she awaits extradition proceedings.