Health Secretary Robert F. Kennedy Jr. accepted $4 million in book advances and more than $270,000 in gifts over the past year from close allies advancing his Make America Healthy Again agenda, according to his latest financial disclosure form. Ethics experts said the financial relationships may violate federal rules barring officials from profiting from their government position, and call into question the secretary’s ability to remain independent and impartial.

The advances were for two books published by a company owned by Tony Lyons, a longtime friend and business associate of Mr. Kennedy who also leads MAHA-related entities. Cheryl Hines, Mr. Kennedy’s wife, accepted $210,000 in consulting fees from MAHA Action, a nonprofit advocacy group also led by Mr. Lyons. It rallies supporters and backs health-related legislation, including a federal bill to end liability protection for vaccine makers.

In an ethics filing before taking office, Mr. Kennedy pledged not to “engage in any writing, editing or promotional activities” associated with the books, but did not promise to forgo advances. Ethics experts said payments related to “Unsettled Science” raised questions since federal rules say an official may not receive compensation for writing a book related to his official duties while in office.

Additionally, the consulting fees to Ms. Hines “reeks of conflict of interest,” and could appear to be a bribe, said Richard Painter, a White House ethics counsel under President George W. Bush. The disclosure also showed Mr. Kennedy accepted $126,000 worth of lodging in a Washington, D.C., home owned by Gavin de Becker, a longtime friend.