US cybersecurity officials on Thursday said Amazon, Google and Microsoft have enlisted to help them fight ransomware and defend cloud computing systems from hackers.

The tech giants are among firms signed on to be part of a Joint Cyber Defense Collaborative intended to combine government and private skills and resources to fight hackers, according to the Cybersecurity and Infrastructure Security Agency (CISA).

"With these extraordinarily capable partners, our initial focus will be on efforts to combat ransomware and developing a planning framework to coordinate incidents affecting cloud service providers," said CISA director Jen Easterly.

US President Joe Biden last week expressed concern about the recent increase in cyberattacks, including via ransomware, which typically see hackers encrypting victims' data and then demanding money for restored access.

"If we end up in a war, a real shooting war, with a major power, it's going to be as a consequence of a cyber breach," Biden said.

Easterly introduced the new collaborative at a Black Hat cybersecurity conference in Las Vegas, where professionals from across the industry met to share research and innovations.

"Damages from cybercrime is costing the world trillions; and ransomware has become a scourge," Easterly said in a keynote presentation at the event.

"I want to focus on strengthening the government's collaboration with the private sector -- industry, academia, researchers, hackers."

The new center will be involved in coordinating national cyber defense and sharing insights into threats, as well as take part in joint exercises, according to CISA.

Easterly urged more computer security firms to join the collaborative effort.

The list of those who have already signed on includes Amazon Web Services, AT&T, Crowdstrike, FireEye, Google and Microsoft.