WASHINGTON — The federal government’s top ethics official has taken the unusual step of sending a letter to the Environmental Protection Agency questioning a series of actions by Administrator Scott Pruitt and asking the agency to take “appropriate actions to address any violations.”

The letter, sent to Kevin Minoli, the E.P.A. official designated as the agency’s top ethics official, addresses questions about Mr. Pruitt’s rental for $50 a night of a condominium linked to an energy lobbyist, as well as his government-funded flights to his home state of Oklahoma. The letter also cites reporting last week in The New York Times that agency staff members who raised concerns about these and other actions found themselves transferred or demoted.

“The success of our government depends on maintaining the trust of the people we serve,” said David J. Apol, acting director of the Office of Government Ethics, in the letter sent Monday morning to the E.P.A. “The American public needs to have confidence that ethics violations, as well as the appearance of ethics violations, are investigated and appropriately addressed.”

The letter walks through the three areas of concern. The first is related to the Capitol Hill condo Mr. Pruitt rented early last year from the wife of an energy lobbyist whose firm had business matters before the E.P.A.