March 20 (Reuters) - UnitedHealth Group ( UNH ) said on

Wednesday its unit Change Healthcare's cloud-based services for

handling medical claims were completely rebuilt and restored,

about a month after a cybersecurity attack on the subsidiary

crippled healthcare in the United States.

Amazon's ( AMZN ) cloud services for two of Change

Healthcare's applications were restored from backups and cleared

by their cybersecurity partners, the insurer said.

Change's Assurance and Relay Exchange are cloud-hosted

applications that rely on authentication services. Assurance is

a medical claims and remittance management software, while Relay

Exchange acts as a clearinghouse which checks insurance claims

for errors.

The services were "completely rebuilt" with the help of

cybersecurity firm Palo Alto Networks ( PANW ) and reviewed by

Google-owned peer Mandiant, the company said, adding these were

being monitored by at least two scanning services.

"We have taken every precaution and safety measure and

implemented several rounds of security protocols - both

internally and with our third-party partners - to ensure

complete confidence in the platform," UnitedHealth ( UNH ) said.

Change Healthcare, which processes about 50% of medical

claims in the U.S. for around 900,000 physicians, 33,000

pharmacies, 5,500 hospitals and 600 laboratories, was breached

on Feb. 21 by a hacking group called ALPHV, also known as

"BlackCat".

With about 1 in 3 U.S. patient records handled by Change's

health technology offerings, the cyberattack sent shockwaves

across the nation's healthcare system and is now under

investigation by the government health department.

UnitedHealth ( UNH ) said on Monday it will start releasing its

medical claims software and it has advanced payments of over $2

billion so far to provide assistance to healthcare providers

financially affected by the hack.

The company had also suspended paperwork required to get

approval for insurance coverage for most outpatient services, as

well as the review of inpatient admissions for government-backed

Medicare Advantage plans, to help those impacted.