U.S. Federal Reserve Chairman Jerome Powell said on Friday that "the tariff increases will be significantly larger than expected."

Powell made the remarks in a speech to the Society for Advancing Business Editing and Writing annual conference in Arlington, Virginia.

"While uncertainty remains elevated, it is now becoming clear that the tariff increases will be significantly larger than expected. The same is likely to be true of the economic effects, which will include higher inflation and slower growth. The size and duration of these effects remain uncertain," Powell said.

"While tariffs are highly likely to generate at least a temporary rise in inflation, it is also possible that the effects could be more persistent," he continued.

The Fed chair's remarks came as U.S. stocks were battered by a steep sell-off Friday amid concerns about a global trade war due to President Donald Trump's sweeping tariffs on U.S. trading partners.

The Dow plummeted 5.5 percent, while the broader S&P 500 dropped 5.97 percent. The tech-heavy Nasdaq Composite fell 5.82 percent, now down over 20 percent from its December peak.