Presidential hopefuls Hillary Clinton and Bernie Sanders ratcheted up their attacks in a bruising, final debate before next Tuesday’s New York primary.

The Democratic race has turned increasingly negative in recent days as the candidates traded barbs about their qualifications for the presidency.

They also clashed on Wall Street banks, gun controls and the minimum wage.

Mr Sanders has won seven of the past eight contests, but Mrs Clinton holds a clear lead in race for the nomination.

The Vermont senator has now headed to Rome where he will make a speech at a conference hosted by the Vatican, but he is not expected to meet Pope Francis.

His supporters gathered at the Vatican awaiting his arrival, wearing T-shirts saying: “Rome feels the Bern.”

Before he left New York, he held a fractious debate with his rival.

“Does Secretary Clinton have the experience and intelligence to be president? Of course she does,” Mr Sanders said at the debate. “But I do question her judgement.”

Mr Sanders repeatedly criticised Mrs Clinton for her financial ties to Wall Street, particularly her paid speeches to an investment bank. He also faulted her for supporting the Iraq War.

Meanwhile, Mrs Clinton has questioned whether Mr Sanders has adequately thought out his policy proposals after he struggled to provide specifics during an interview with the New York Daily News.

“It’s easy to diagnose the problem. It’s another thing to do something about it,” Mrs Clinton said.

The candidates’ recent tensions were on display on stage. Mr Sanders mocked Mrs Clinton’s responses at times while Mrs Clinton occasionally talked over her opponent.

Other highlights included:

  • Mrs Clinton refused Mr Sanders’ demand to release the transcripts of paid speeches she has given to Wall Street companies, saying she would do so only when all other candidates did the same
  • Mrs Clinton demanded Mr Sanders release his tax returns, saying she had published 30 years’ worth and it was expected of all candidates. Mr Sanders promised to release them on Friday
  • Mrs Clinton aggressively criticised Mr Sanders’ record on gun control, pointing out he voted to shield gun makers from legal liabilities
  • Mr Sanders spoke passionately about the threat of climate change. “Those little steps are not enough,” he said of the policies of the Obama administration
  • Mrs Clinton defended her role in the US intervention in Libya; Mr Sanders faulted her for the breakdown in security in that country
  • Mr Sanders called for European allies to contribute more financial support to Nato, echoing sentiments from Republican front-runner Donald Trump
  • “We can’t continue to be one sided,” Mr Sanders said of America’s role in solving the Israeli-Palestinian conflict
  • Mrs Clinton offered a full-throated defence of abortion rights, eliciting cheers from the crowd