China expressed firm opposition on Monday to the United States' sanction against a Beijing-based cybersecurity company that Washington has accused of helping Chinese hackers infiltrate US communications systems, and it vowed to take necessary measures to safeguard its legitimate rights and interests.

The US Department of the Treasury said in an announcement on Friday that a company called Integrity Technology Group had supported a Chinese hacking group known as Flax Typhoon in a campaign to break into foreign networks between the summer of 2022 and 2023.

Foreign Ministry spokesman Guo Jiakun slammed the accusations, saying at a daily news conference that China always firmly opposes and has cracked down on cyberattacks in accordance with law. It urges the US to stop using the issue to defame and smear China, he said.

"For some time now, the US has been playing up so-called Chinese hacker attacks and has even imposed illegal unilateral sanctions against China," Guo said.

Integrity Technology Group said the move by Washington had "no factual basis", and that it firmly opposes the unwarranted accusations and illegal unilateral sanctions, The Associated Press quoted the company as saying in a statement to the Shanghai Stock Exchange.

This is the second time since December that Washington has sanctioned Chinese companies that it suspects of involvement in cyberattacks. The US Treasury Department sanctioned Chengdu-based Sichuan Silence Information Technology Co and one of its employees last month.

zhoujin@chinadaily.com.cn