Outgoing US President Joe Biden on Tuesday branded his successor Donald Trump's economic plans a "disaster," in a speech hailing his own legacy.

Biden said Trump's threats to slap huge tariffs on imports were a "major mistake" and challenged Trump to build on what he said were the successes of his own administration.

The lame-duck president's speech comes after Trump won a second term largely on the back of US voters' anger at high costs of living under Democrats.

"I pray to God the president-elect throws away Project 2025. I think it'd be an economic disaster for us and the region," Biden said at the Brookings Institution in Washington, referring to a conservative blueprint for a second Trump administration.

Coughing frequently because of a cold, Biden said US consumers would pay the price for the tariffs that Trump has vowed to slap on US neighbors Mexico and Canada and on Asia-Pacific rival China.

Together they are the three biggest US trading partners.

"I believe this approach is a major mistake," Biden added.

At a separate event Tuesday, Treasury Secretary Janet Yellen said Trump's tariffs could "derail the progress that we've made on inflation, and have adverse consequences on growth."

She warned at the Wall Street Journal's CEO Council Summit that sweeping tariffs could raise prices significantly for US consumers and pile pressure on companies which rely on imports.

The White House touted Biden's speech as a "major address on his economic legacy" as the 82-year-old looks to the history books with fewer than six weeks left in office.

Biden dropped out of the 2024 presidential race against Trump in July due to concerns about his age and passed the torch to Vice President Kamala Harris, whom Trump comfortably defeated at the November polls.

Trump's inauguration is not until January 20, but he has already become something of a shadow president, making pronouncements on the economy and foreign policy and being feted by world leaders.

Biden has kept a relatively low profile, but he came out swinging in defense of his own record before an audience of economists.

He contrasted his "middle-out, bottom-up economic playbook" with what he called Trump's failed promise of "trickle-down economics" in which tax cuts for the wealthy are supposed to boost incomes.

Biden also touted achievements including the US economy's recovery from the Covid pandemic and his huge investments in green technology and industry.

"President-elect Trump is receiving the strongest economy in modern history," said Biden.

But the departing president said he regretted not signing his name to Covid stimulus checks sent out to Americans, like Trump had done.

Biden ended his speech with a broader plea for US leadership in a troubled world, even as Trump has repeatedly signaled his intention to take a more isolationist stance.

"If we do not lead the world, what nation leads the world?" he said.