April 4 (Reuters) - Peter Marks, the FDA's top vaccine official ousted by Robert F. Kennedy Jr. said the U.S. health secretary's team sought nonexistent data to justify antivaccine narratives, the Wall Street Journal reported on Friday.

Kennedy, a well-known vaccine skeptic, last week announced plans to reshape federal public health agencies, including cutting jobs of 10,000 employees and centralizing some functions of the FDA, CDC and others under his purview.

Marks is the highest-profile exit at the FDA amid the Donald Trump administration's overhaul.

According to the WSJ report, Marks said he did not want to leave and sought to collaborate with the health secretary. Marks sent a memo to the U.S. Food and Drug Administration's acting commissioner early in Kennedy's tenure that proposed listening sessions on vaccines and making immunization information clearer for parents and doctors.

In early March, Kennedy's team requested that Marks turn over data on cases of brain swelling and deaths caused by the measles vaccine - data that Marks said does not exist because there have been no such confirmed cases in the U.S, the report added.

In the report, Marks said Kennedy's team was also interested in weakening regulation of unproven stem-cell treatments, which are sold for diseases ranging from Alzheimer's to arthritis. He proposed a new set of regulations that would keep rules vigorous for risky treatments but more lenient for less risky therapies.

Marks said if these stem cells are made improperly they can harm people.

New FDA Commissioner Marty Makary supported the decision to topple Marks, the report said, citing people familiar with the matter.

The FDA also sat on a vaccine application its staff scientists had been poised to approve, missing a key deadline, and Makary was involved in the decision to hold off on the approval, the WSJ's report said, citing a person familiar with the matter.

On Wednesday, Novavax ( NVAX ) said the FDA missed its deadline for making a decision on the traditional approval of the company's COVID-19 vaccine.

The HHS and Marks did not immediately respond to Reuters' requests for comment. (Reporting by Puyaan Singh in Bengaluru; Editing by Maju Samuel)