A hacking group has leaked a collection of powerful hacking tools allegedly used by the US' National Security Agency online.

According to experts, the leaks, published by the Shadow Brokers on Friday, target a variety of Windows servers and Windows operating systems, including Windows 7 ' title=' Windows 7 '>Windows 7 and Windows 8.

"They may have been used to target a global banking system. One collection of 15 exploits contains at least four Windows hacks that researches have already been able to replicate," the experts said.

"This is quite possibly the most damaging thing I've seen in the last several years," said Matthew Hickey, founder of security firm Hacker House.

"This puts a powerful nation state-level attack tool in the hands of anyone who wants to download it to start targeting servers."

The Shadow Brokers is a group of anonymous hackers that published hacking tools used by the NSA last year.

On April 8, the group published a batch of NSA exploits it had previously tried, and failed, to sell.

This Friday's release contains more serious exploits. The releases are published with strange and misspelled blog posts.

According to Hickey, the Windows exploits could be used to conduct espionage and target critical data in Windows-based environments.

A Microsoft spokesperson told CNN that they were reviewing the report and will "take the necessary actions to protect our customers".