NEW YORK (Reuters) - Humana Inc, one of the largest U.S. providers of Medicare Advantage healthcare plans for older people, said on Tuesday that it believes a previously disclosed government query for information is part of a wider review involving many healthcare companies.

Humana first said the U.S. Department of Justice had asked it to volunteer information about risk adjustment matters on Feb. 18.

"Humana believes that this request for information is in connection with a wider review of Medicare risk adjustment generally that includes a number of Medicare Advantage plans, providers and vendors," the company said in a regulatory filing on Tuesday.

The disclosure came the morning after DaVita Healthcare Partners Inc said in a regulatory filing that its JSA Medical Group unit had received a subpoena from the U.S. Department of Health and Human Services' Office of Inspector General.

JSA provides medical services through clinics and pharmacies. DaVita said it had been advised by a Justice Department lawyer that the subpoena related to a civil investigation of Humana and its service providers' risk adjustment practices and data including patient diagnoses.

DaVita said the time period involved was from 2008 through 2013 and that the subpoena related in particular to two Florida physicians that had previously contracted with it.

The government makes risk adjustment payments to Humana and other companies that provide Medicare Advantage when they have patients who are sicker than average.

“As matter of policy, the department generally neither confirms nor denies the existence of an investigation,” Justice Department spokeswoman Nicole Navas said.

Susquehanna analyst Chris Rigg said in a research note that the Humana disclosure fit with the DaVita request and a notice to insurers from a Health and Human Services division earlier this year about its review of the use of patient in-home risk assessments by insurers.

Humana shares were up 0.4 percent at $182.77 in morning trading. DaVita was down 0.6 percent at $82.32.

(Reporting by Caroline Humer; Additional reporting by Lindsay Dunsmuir in Washington D.C.; Editing by Lisa Von Ahn)