EPA Administrator Scott Pruitt testifies before the House Appropriations Committee Subcommittee on Interior, Environment, and Related Agencies Subcommittee on Capitol Hill in Washington, U.S., April 26, 2018. REUTERS/Aaron P. Bernstein

WASHINGTON (Reuters) - The U.S. Environmental Protection Agency’s inspector general office told Democratic lawmakers it will open a probe of Administrator Scott Pruitt’s controversial housing arrangement with a lobbyist and other matters, according to a letter they circulated on Friday.

“We have received multiple requests from multiple members of Congress, as well as other Office of the Inspector General Hotline complaints, regarding these same and related issues,” Inspector General Arthur Elkins wrote to Democratic Congressmen Ted Lieu (California) and Don Beyer (Virginia).

The letter, sent on Wednesday, was released a day after Pruitt faced tough questions regarding a string of recent ethics and spending concerns in nearly six hours of hearings in the U.S. House of Representatives.

The new probe is in response to a number of concerns outlined by the Office of Government Ethics to the EPA’s designated ethics official, who turned the letter over to the inspector general’s office “for action.”

The concerns include Pruitt’s 2017 housing arrangement in which he paid $50 per night to the wife of a lobbyist for his lodging in Washington, reports of high spending for travel, use of staff and expenditures for enhanced security measures and reassignment of staff who flagged concerns about improper spending.

Elkins said some of the matters will be addressed in ongoing reviews and others will trigger new probes.

There are currently 10 open investigations involving various ethical and spending issues related to Pruitt in the EPA’s inspector general’s office, the White House and Congress.