Key moments from Joe Biden's gaffe-filled press conference #joe biden

Joe Biden batted away questions about his fitness for office in a highly-anticipated press conference, saying he is the most qualified person to run for United States president, after mistakenly referring to the Ukrainian leader as "President Putin" and his rival Donald Trump as his "vice-president".

Biden addressed reporters on a wide range of topics on the sidelines of the NATO summit in Washington DC, in what was billed as a high-stakes news conference on Friday morning (AEST).

Biden and his supporters hoped his performance would ease fears about the 81-year-old's age and mental acuity.