Vermont Senator Bernie Sanders has said that Hillary Clinton must become the next president of the United States, in a speech at the Democratic Convention in Philadelphia.

Bernie Sanders received a three-minute standing ovation when he took the stage.

First Lady Michelle Obama also received a rapturous reception for a powerful speech in which she took on Republican nominee Donald Trump.

“Don’t let anyone ever tell you that this country isn’t great, that somehow we need to make it great again,” Michelle Obama said, referring to Donald Trump’s signature slogan “Make America Great Again”.

“Because this, right now, is the greatest country on earth,” the First Lady added.

Earlier in the evening, Bernie Sanders’ fans had booed any mention of Hillary Clinton, who will accept the party’s presidential nomination on July 28.

And as he urged Democrats to back Hillary Clinton, his former rival, in the final major speech of the night, they held aloft their blue “Bernie” signs and chanted his name.

Some supporters broke into tears while others wore duct tape emblazoned with the words “silenced” over their mouths.

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Bernie Sanders continued: “While Donald Trump is busy insulting one group after another, Hillary Clinton understands that our diversity is one of our greatest strengths.

“If you don’t believe this election is important, if you think you can sit it out, take a moment to think about the Supreme Court justices that Donald Trump would nominate and what that would mean to civil liberties, equal rights and the future of our country.”

Members of the audience had earlier disrupted the event’s opening prayer, chanting “Bernie!” while also jeering as Democratic National Committee chair Marcia Fudge delivered remarks.

The commotion prompted Bernie Sanders to send an email saying the credibility of the progressive movement would be damaged by “booing, turning of backs, walking out or other similar displays” of protests.

Revelations from an email leak which showed DNC officials allegedly plotted against Bernie Sanders’ primary campaign threatened to overshadow the event as it fuelled the anger of his voters.

WikiLeaks released emails that revealed the DNC was biased against Bernie Sanders when he ran against Hillary Clinton in the hard-fought primary contest.

The FBI has confirmed that it is investigating the leak.

Democratic chairwoman Debbie Wasserman Schultz resigned on July 24 as pressure built on the party to address the scandal.

Democratic party bosses later issued an apology to Bernie Sanders for “inexcusable” emails which tried to undermine his White House campaign.

However, Bernie Sanders refused to let the email scandal eclipse his message to his supporters.

“Hillary Clinton will make an outstanding president and I am proud to stand with her here tonight,” said the Vermont senator before leaving the stage.

About 5,000 party delegates are among the 50,000 people expected to attend the four-day Democratic convention, which will end on July 28 with Hillary Clinton formally accepting the nomination for president.