A security researcher who helped curb a global outbreak of the WannaCry ransomware earlier this year has told a court he is not guilty of charges of allegedly creating a notorious banking malware.

Marcus Hutchins. (Image: file photo)

Marcus Hutchins, 22, said he was not guilty during a hearing at a Las Vegas court after he was arrested and detained earlier this week.

The news was confirmed by his attorney Adrian Lobo, speaking on Facebook Live to local reporter Christy Wilcox, at the court house.

Hutchins was granted bail on a bond of $30,000 during a hearing at a Las Vegas court.

But he will "not be released today lawyers says could not get bail in time," according to Wilcox in a tweet.

He will not be allowed access to devices with an internet connection, said Wilcox, and he will be tagged to be monitored at all times.

Hutchins, also known as @MalwareTechBlog, stormed to fame earlier this year after he found a kill switch in the malware, known as WannaCry, amid a global epidemic of ransomware in May.

By registering a domain found in the code, he stopped the spread of the malware.

The Justice Department announced Thursday that it was charging Hutchins with malicious activity, unrelated to the WannaCry cyberattack.

The security researcher, a British native, was arrested shortly before boarding a flight home. He had been attending the Def Con security conference late last month. He was briefly detained in a federal detention facility in Nevada, then later questioned by the FBI at its field office in Las Vegas.

Hutchins was later indicted, along with an unnamed defendant, on six charges relating to allegations that he created the Kronos malware, a trojan that can steal banking usernames and passwords from victims' computers.

He was also charged with five other counts, including wiretapping -- thought to relate to the interception of passwords; and violating the controversial Computer Fraud and Abuse Act, which serve as the basis of US hacking laws.

Hutchins will appear at a court in Wisconsin, where the case was filed, on August 8.

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