The US Federal Bureau of Investigation (FBI) Director Christopher Wray has revealed that Chinese hackers outnumber FBI cyber staff 50 to one.
The disclosure came as the US and other countries are facing immense cyber threats, particularly from China.
"To give you a sense of what we're up against, if each one of the FBI's cyber agents and intel analysts focused exclusively on the China threat, Chinese hackers would still outnumber FBI Cyber personnel by at least 50 to 1," Wray said during a House Appropriations subcommittee meeting, reports CNBC.
China has "a bigger hacking programme than every other major nation combined and has stolen more of our personal and corporate data than all other nations -- big or small -- combined," he told the Congress panel.
Other countries like Russia, Iran and North Korea also pose significant cybersecurity concerns.
The FBI is currently probing more than 100 "ransomware variants" with "scores of victims" for each.
At least 30,000 organisations across the US, including government and commercial firms, were hacked by China-based threat actors in 2021 who used Microsoft's Exchange Server software to enter their networks.
According to KrebsOnSecurity, the China-based espionage group exploited four vulnerabilities in Microsoft Exchange Server email software.
The vulnerabilities allowed hackers to gain access to email accounts, and also gave them the ability to install malware, according to Microsoft which reported about the China-based threat actors but did not reveal the scale at which tens of thousands of organisations have been hit.
Nine federal agencies and about 100 private sector companies were compromised as a result of an earlier SolarWinds hack, the White House had said.
In a widespread cyber-attack on US federal agencies and enterprises via SolarWinds software, hackers also broke into the networks of NASA and the Federal Aviation Administration (FAA).