(Reuters) -Federal Reserve Chair Jerome Powell on Thursday responded to a Trump administration official's demands for information about cost overruns for a renovation project at the central bank's Washington headquarters campus, saying the project was large in scope and involved a number of safety upgrades and hazardous materials removals.

"As explained on the Board's public website, we take seriously the responsibility to be good stewards of public resources as we fulfill the duties given to us by Congress on behalf of the American people," Powell wrote in his letter to Office of Management and Budget Director Russell Vought. "We have taken great care to ensure the project is carefully overseen since it was first approved by the Board in 2017."

He noted that the project's budget is subject to annual approval by the Fed Board and that the Fed's inspector general has full access to information on costs and other details.

Vought last week accused Powell of overseeing an "ostentatious" and costly overhaul of the buildings, and demanded answers from Powell to a series of questions about the project, which has emerged as the latest line of attack against Powell by the Trump White House. 

"Dear Mr. Vought," Powell said in his letter, "both buildings were in need of significant structural repairs and other updates to make the buildings safe, healthy, and effective places to work, including the removal of asbestos and lead contamination, complete replacement of antiquated systems such as electrical, plumbing, heating, ventilation, and air conditioning, as well as fire detection and suppression systems."

The project did not include private elevators or VIP dining rooms, or new marble except where the original was damaged "or where needed to keep with historic preservation guidelines and to address concerns raised by external review agencies," Powell said.

Trump, who wants Powell gone from the Fed because he hasn't delivered interest-rate cuts, has raised the renovation project as a possible fresh reason for ousting the Fed chief, suggesting there could be fraud without providing evidence. Vought has said that administration officials are trying to visit the site to inspect it.

"It's for a big, beautiful mansion for the Federal chairman," White House spokeswoman Karoline Leavitt said during a White House press briefing on Thursday. "It's completely unnecessary. It's overpriced, and I think it's a good thing the administration, led by the president, is looking into it."

Leavitt was asked if the review finds any wrongdoing, will it trigger the president to fire Powell. "Look, it's a hypothetical question. We'll see where it goes," Leavitt said.

Powell's letter was largely a reiteration of what he told members of the Senate Banking Committee earlier this week, and of detailed explanations on the Fed's website of the project countering Vought's assertions that changes to the project violated rules set by the National Capital Planning Commission and required the commission's review.

The Fed has worked closely and collaboratively with the NCPC, Powell said, and the changes that the Fed has made were not substantial and therefore did not meet the NCPC's own guidance for what would need additional review.