(Reuters) - About 400 U.S. Food and Drug Administration staffers have returned to their posts from furlough, including some food inspectors and support professionals, Commissioner Scott Gottlieb said in a tweet on Tuesday.

FILE PHOTO: FDA Commissioner Scott Gottlieb speaks during an interview with Reuters in New York City, U.S., November 26, 2018. REUTERS/Brendan McDermid/File Photo

Gottlieb’s comments come as the longest U.S. government shutdown, triggered by President Donald Trump’s demand for $5.7 billion from Congress to fund a wall on the border with Mexico, reached its 25th day.

The FDA employees returning to work, mostly without pay, include about 100 staff focused on inspections of high-risk medical device manufacturing facilities, about 70 focused on inspections of high-risk drug manufacturing facilities and about 90 focused on inspections of high-risk biological manufacturing facilities, Gottlieb said here.

About 150 of the returning staffers are involved with inspections of food deemed potentially high risk, Gottlieb said. Those would include seafood, baby formula and some fruits and vegetables.

Reviews to determine whether new medicines warrant approval are also likely to be impacted by the shutdown.

“We expect drug manufacturers could face near-term regulatory gridlock and the potential for a backlog of delayed filings, meetings, and regulatory decisions that could extend even beyond the end of the shutdown,” RBC Capital Markets analyst Brian Abrahams said in a note, adding that Regeneron Pharmaceuticals and Celgene Corp are among drugmakers that could be adversely affected.

Drug applications requiring user fees will continue to be reviewed if submitted prior to the start of the shutdown, as the agency would be able to use carryover funding from 2018, Gottlieb said. That would not include certain medicines, such as allergy treatments.

Aimmune Therapeutics Inc said on Monday that review of its peanut allergy treatment was being delayed.

Calls to the FDA seeking comment were met with messages saying the various spokespeople were on furlough status and unable to take the call.

Gottlieb, who has been tweeting updates on work at the FDA during the shutdown, indicated on Monday that the agency would restart some inspections by largely unpaid staff.

He said the agency has funding that would last about five weeks and will focus on critical activities.

“We continue to operate the programs using carryover user fees, and we’ll prioritize work that impacts public safety, as this is our foremost priority,” Gottlieb said.

Without funding, Gottlieb warned, programs aimed at bringing cheaper generic drugs and biosimilars to market would be impacted.