Exxon Mobil to pay $32.2 mln in whistleblower case

* Exxon Mobil units accused of underpaying royalties

* Private citizen had filed lawsuit

NEW YORK, April 5 (Reuters) - Exxon Mobil Corp (XOM.N) will pay $32.2 million to the United States to resolve claims that some of its units knowingly underpaid royalties owed on natural gas, the Justice Department said on Monday.

The government alleged that Mobil Natural Gas Inc, Mobil Exploration & Producing U.S. Inc and affiliates underreported the value of natural gas taken from federal and American Indian leases between March 1, 1988 and Nov. 30, 1999.

As a result, the Mobil entities paid lower royalties than they owed to the United States and to American Indian tribes, the government said. The Mobil entities became part of Exxon Mobil through a 1999 merger.

Exxon Mobil, based in Irving, Texas, did not immediately return a request for comment.

The case arose out of a lawsuit filed by a private citizen on behalf of the United States under the whistleblower provisions of the federal False Claims Act.

Various other energy companies have agreed to pay more than $200 million to settle their portions of the lawsuit.

The estate of the now-deceased whistleblower, Harold Wright, will receive $975,000 from the Exxon Mobil settlement, the Justice Department said.

Exxon Mobil shares closed Monday up 58 cents at $68.19.

The case is U.S. ex rel. Wright v. Agip Petroleum Co et al, U.S. District Court, Eastern District of Texas, No. 03-00264. (Reporting by Jonathan Stempel)