WASHINGTON (AFP, BLOOMBERG) - US Federal Reserve Chairman Jerome Powell, who has faced bitter criticism from Donald Trump, said in an interview broadcast on Sunday (March 10) that the US president can't fire him.

"The law is clear that I have a four-year term. And I fully intend to serve it," Powell told CBS television's "60 Minutes."

However, Powell refused to criticise Trump or discuss private conversations with him, saying "it would not be appropriate" for him to do so.

"I try not to comment on the president. I just don't think it's appropriate for me to comment on the president or frankly any other elected official," Powell said.

"If I do that, I think it's a distraction from the important job that we have."

Last year, Trump angrily and very publicly denounced the Fed's "crazy" interest rate hikes, breaking with traditional reserve from presidents toward the world's most powerful central bank.

The acrimony was such that it led to talk of Trump planning to fire Powell, even though he was the president's nominee.

Turning toward the economy at large, Powell noted that the US growth rate was expected to slow this year, but denied there was a risk of a recession.

"This year, I expect that growth will continue to be positive and continue to be at a healthy rate," he said.

He said interest rates can remain on hold as the US central bank waits to see how conditions abroad evolve, signaling that there's no clear time limit to the Fed's current pause.

"Inflation is muted and our policy rate we think is in an appropriate place," Powell said. He called the current rate setting "roughly neutral" - meaning its neither stoking nor slowing growth -- and tried to define the Fed's stance of patience while reviewing fresh data.

"Patient means that we don't feel any hurry to change our interest rate policy," he said.

Powell's comments come at a time when the US economy looks solid, inflation is just shy of the Fed's 2 per cent goal, and unemployment is at its lowest level since the 1960s. Still, the Fed in January pivoted from hiking rates to taking a pause amid tighter financial conditions and as risks emerged abroad.

Asked what it would take for the Fed to move borrowing costs up or down, Powell said he and his colleagues will be looking at growth, job creation, wages and inflation domestically, and will keep an eye on China, Europe and events including Britain's ongoing exit negotiations with the European Union.

"We'll be putting that all together and deciding when it will be appropriate to change our policy," Powell said. "What's happened in the last 90 or so days is that we've seen increasing evidence of the global economy slowing down" and "we're going to wait and see how those conditions evolve before we make any changes to our interest-rate policy."

Powell, Vice-Chairman Richard Clarida, Governor Lael Brainard and New York Fed President John Williams have all recently signaled their contentment with letting the policy rate rest at 2.25 per cent to 2.5 per cent when they meet March 19-20, and perhaps even beyond that. Fed officials will submit new rate and economic forecasts at the March FOMC meeting, and those projections could offer clues about whether they still anticipate raising rates later this year.

Investors took Powell's latest comments in stride, with futures on the S&P 500 Index remaining steady in early Monday trading in Asia.

Powell also identified cyber-security as a major risk that the Fed works on constantly, and said the Fed is carefully watching leveraged lending to corporations.

"If there were a downturn, having highly leveraged companies would be an amplifier," he said. "I don't think it's the kind of thing that we saw in the financial crisis."