The Environmental Protection Agency's inspector general is expanding an inquiry into Administrator Scott Pruitt's frequent taxpayer-funded travel, the watchdog office said Friday.



The review will now include all travel by Pruitt through Sept. 30 as the office examines whether Pruitt followed EPA travel policies and whether those policies are sufficient to prevent fraud, waste and abuse. Previously, the inspector general was focusing on Pruitt's travel to his home state of Oklahoma through July 31.



A spokeswoman said Friday the scope of the review was expanded after requests by members of Congress.



EPA documents show Pruitt and his staff chartered a private plane for an Aug. 4 trip from Denver to Durango, Colo., to visit the Gold King Mine, site of a spill last year. Pruitt also took three flights on government-owned planes to New York and North Dakota and for a roundtrip between airports in Oklahoma.



Letters released by EPA show the flights cost a total of $58,000 and were approved by the agency's general counsel's office.



The expanded review came as The Washington Post reported Transportation Secretary Elaine Chao used government planes instead of cheaper commercial airline flights seven times in the past eight months. The revelation was the latest involving Trump administration officials' use of costly private or military air travel at taxpayers' expense.



Tom Price resigned as Health and Human Services secretary last week amid criticism of his pattern of using private charter aircraft for official trips on the taxpayer's dime, instead of cheaper commercial flights.



The Post reported Thursday that Chao used the government planes to fly to Paris for an annual air show and to Sardinia for a meeting of industrialized democracies. Other destinations included cities within an hour's flight of Washington.



Separately, a report by the Treasury Department's inspector general says that Secretary Steven Mnuchin did not violate any law in the seven trips he has taken on government airplanes but did fail to provide enough proof of why he needed to use the more expensive modes of travel. Mnuchin's travel requests included one, later withdrawn, for a government plane for use on his European honeymoon.



The EPA's inspector general opened an inquiry last month into Pruitt's frequent taxpayer-funded travel on commercial planes. The Associated Press reported earlier this year that Pruitt often spends weekends at his Tulsa home.



An EPA spokeswoman said the trips were warranted.



Democratic Reps. Frank Pallone of New Jersey, Diana DeGette of Colorado and Paul Tonko of New York requested the expanded review, saying Pruitt's reported use of private aircraft "is just the latest example of repeated and blatant abuse of taxpayer funds by the Trump administration."