US President Donald Trump reignited his controversial criticism of the US Federal Reserve, calling the Fed his "biggest threat."

Donald Trump followed up previous strong attacks on the Fed by complaining again that interest rates are rising too quickly. 

"My biggest threat is the Fed, because the Fed is raising rates too fast," he told Fox Business television. 

Trump acknowledged that the Fed is independent, "so I don't speak to them," but then leveled direct criticism at Fed Chairman Jerome Powell, who he said should be slower on interest rate rises. 

"It's going too fast, because you look at the last inflation numbers - they're very low," he said. 

Trump appointed Powell but told Fox, "maybe it's right, maybe it's wrong." 
"There are a lot of other people there I'm not so happy with," he said. 

The Fed has raised interest rates three times this year as it seeks to prevent a vibrant economy from overheating. 

US presidents usually remain silent on such issues in respect toward the Fed's independence. Trump has previously called Fed policies "crazy."