Former US President Joe Biden on Wednesday sharply criticized the new US administration's approach to Social Security, warning of widening divisions within the country in his first major public address since President Donald Trump's return to the White House.

"We cannot continue as a nation so divided, so divided," Biden, 82, said during the Advocates, Counselors, and Representatives of People with Disabilities conference in Chicago.

He added, "We've never been so divided," referring to the growing gap between Trump supporters and Democrats.