Donald Trump has claimed the "system is rigged" after Bill Clinton's meeting with the US attorney general that came as the justice department concludes its investigation of Hillary Clinton's emails.

Bill Clinton met attorney general Loretta Lynch, whom he installed as US attorney for the Eastern District of New York back in 1999, on the tarmac at Phoenix Airport, in what he claimed was a chance encounter.

Lynch is head of the department of justice, which is currently investigating the use of a private email server by Hillary Clinton in her role as US secretary of state – something the Democrat presumptive presidential nominee could potentially face indictment over.

And Trump, along with many others, was not convinced the meeting between Lynch and Bill Clinton was unplanned – accusations that will surely have dented Hillary's campaign ahead of the Democrat primary at the end of July.

Trump tweeted: "Crooked Hillary Clinton knew that her husband wanted to meet with the USAG to work out a deal. The system is totally rigged & corrupt!"

Hillary Clinton
Democratic presidential candidate Hillary Clinton and her husband former US president Bill Clinton greet supporters during a primary night event in Brooklyn, New YorkJustin Sullivan/ Getty

Lynch herself has denied there was anything untoward about the encounter, telling the Washington Post the subject of the investigation into Hillary Clinton's emails did not come up.

"The fact that the meeting that I had is now casting a shadow over how people are going to view that work is something that I take seriously, and deeply and painfully," she told the paper.

Clinton faced three hours of questioning by the FBI last weekend (2 July) over her email usage, and it is now looking less likely the Democrat candidate will face charges, sources told CNN.

The end of the review into the emails and rumours Clinton will not face indictment may have led to Trump's social media outburst, and it is believed he expected Clinton to face some kind of charges over the email issue.