FARMVILLE: Democrat Tim Kaine accused Republican presidential nominee Donald Trump of breaking a promise to release his tax records in a debate on Tuesday where the vice presidential contenders bickered and interrupted each other.

Trump's vice presidential nominee, Mike Pence, defended Trump days after a New York Times report gave ammunition to the Democratic case against Trump by reporting he may not have paid federal taxes for 18 years.

The debate at Longwood University in Farmville, Virginia, was lively from the start as Kaine, the running mate of Democratic presidential nominee Hillary Clinton, honed in on Trump's refusal thus far to reveal his tax records, saying he had broken a promise to do so.

Trump has said they are under federal audit.

"Governor Pence had to give Donald Trump his tax returns to show he is qualified to be vice president. Donald Trump has to give his tax returns to show he is qualified to be president," Kaine said.

Pence, who has a low-key style compared to Trump's signature bombast, said Trump as a New York real estate developer had created thousands of jobs and had used US tax laws as they were designed to be used.

"Why won't he release his taxes?" Kaine shot back.