March 4 (Reuters) - A court-appointed special master has

found that U.S. authorities do not have evidence to support

their billion-dollar fraud case accusing UnitedHealth Group ( UNH )

of keeping overpayments from the government for patients

on its Medicare insurance plans.

The recommendation by Special Master Suzanne Segal on Monday

is not a final ruling, but if it is adopted by U.S. District

Judge Fernando Olguin, it would end the U.S. Department of

Justice's claims against the health insurer.

"After more than a decade of DOJ's wasteful and expensive

challenge to our Medicare Advantage business, the Special Master

concluded there was no evidence to support the DOJ's claims we

were overpaid or that we did anything wrong," UnitedHealth ( UNH ) said

in a statement.

The Justice Department did not immediately respond to a

request for comment.

The government claimed in its 2016 lawsuit that UnitedHealth ( UNH )

submitted false diagnoses for patients on its government-funded,

privately administered Medicare Advantage plans in order to get

higher payments. Medicare reimbursements to insurers that

administer Medicare Advantage plans are tied to patients'

diagnosis codes, with sicker patients getting higher

reimbursements.

However, Segal wrote on Monday that the government's case

relied on discrepancies between diagnoses submitted by doctors

making claims and later determinations by UnitedHealth's ( UNH ) coders.

She said that did not show that any of the original claims were

false, concluding that there "simply was no fraud."