The warnings were issued in at least three separate division meetings, according to transcripts of the meetings seen by Reuters, as most of the FDA's roughly 18,000 employees prepare to start full-time office work.

In Thursday's meeting, Jacqueline Corrigan-Curay - director of the FDA's Center for Drug Evaluation and Research - said plans for coming layoffs were being made by the Department of Health and Human Services with input from acting FDA commissioner Sara Brenner.

She said Brenner is an advocate for the FDA who understands user fees and the unique skill set of the agency's employees. "But I do not have any insight into" the plans.

U.S. federal agencies including the HHS, which oversees the FDA and Centers for Disease Control and Prevention, are due to submit layoff plans to the Trump administration on Thursday.

Neither HHS nor FDA immediately responded to requests for comment.

President Donald Trump and billionaire ally Elon Musk, who oversees the so-called Department of Government Efficiency, have been gutting agencies as part of an effort to shrink the federal bureaucracy. They fired around 1,000 probationary FDA employees last month before bringing some back. Reuters could not confirm the final number of staff fired.

Trump issued a mandate earlier this year that federal agencies terminate remote or hybrid work arrangements, which required all FDA staff who live within 50 miles (80.5 km) of a facility to work from them after March 17. Staff who live further away were given until April 28.

The FDA has long allowed some employees to work from home, but like many organizations expanded remote work and gave away office space, including a main building for the Center for Tobacco Products, following the COVID-19 pandemic.

Some staff for the FDA’s centers for medical devices and tobacco products who live near the agency's headquarters in Silver Spring, Maryland, close to Washington, will work in the same building as of Monday, executives at the divisions said in two separate meetings.

EXPECT LONG WAITS

The Trump administration last week also said it was considering selling some government buildings, posting a directory of those up for possible sale that included some FDA facilities, which has since been taken down.

Jaime Horman, deputy office director for the FDA's center that regulates medical devices, said in a meeting on Wednesday that staff based in offices due to be sold would be allowed to keep working remotely until the agency finds them a new location.

Some FDA field workers have yet to be assigned an office this week or have been told to report to locations far from their homes, according to sources. One source said a colleague in Hawaii had been assigned to a facility more than 2,000 miles (3,219 km) away in San Francisco with less than a week's notice.

FDA executives said headquarters staff might need to park on the street due to limited spaces, and encouraged them to use carpools and public transportation as much as possible. Horman said the FDA expected to have stacked parking in the future.

Returning staff should expect crowds and long waits to clear enhanced security when they arrive at the Silver Spring campus, and should only bring essentials such as laptops and docking stations, the executives said.

Officials for the FDA's tobacco and medical devices centers said with not enough workspace seating for all field staff, some may be forced to work at conference room tables with other employees.

Workspaces at headquarters and other locations might not be fitted with docking stations or computer monitors, cautioned the medical devices official.

A representative from the National Treasury Employees Union, which represents HHS workers, in one meeting encouraged staff to document working conditions including the time it took to find parking and get through security.