U.S. President Donald Trump urged the speedy release of emails hacked from Democrats during the 2016 election campaign, newly-released documents from special counsel Robert Mueller's investigation indicate.

The Justice Department released 500 pages of interview summaries, emails and other documents related to Mueller's report on Saturday after a court battle with BuzzFeed and CNN.

The documents include summaries of FBI interviews with Trump's deputy campaign chair Rick Gates, his campaign chairman Paul Manafort, former campaign lawyer Michael Cohen and Steve Bannon, the former presidential adviser.

Why was Trump team 'euphoric'?

The notes suggest Trump and his aides were frustrated that WikiLeaks was slow in releasing Democratic National Committee (DNC) emails that the Trump campaign was told WikiLeaks had obtained and discussed how to access to them.

When WikiLeaks did dump a series of documents, Gates said the campaign's response was "euphoric."

Gates also claimed that Trump once said "get the emails" while on his campaign plane and on another occasion told him "more leaks were coming," according to Buzzfeed. 

In July 2017, Trump publicly asked Russia for help finding emails his election rival Hillary Clinton had not made public during a State Department inquiry into her use of a private email server. Trump later backtracked, telling Fox News he was "being sarcastic."

"Trump was generally frustrated Clinton's missing emails had not been found," Gates said in an interview, the notes show.

The documents also include email correspondence between Bannon and Jared Kushner, Trump's adviser and son-in-law, as well as a "proposal to obtain" and analyze emails belonging to Clinton, which was sent to Bannon by conservative activist Barbara Ledeen.

What else do the notes reveal?

The documents show that Gates told investigators on April 10, 2018 that Manafort pushed the idea that the hack of DNC emails was "likely" carried out by Ukrainians, not Russians, during the 2016 campaign.

Trump's allies later promoted that theory to undermine Mueller's conclusions about Russian interference, but it has been discredited.

The House of Representatives' impeachment probe of the president is looking at whether Trump improperly pressured Ukraine President Volodymyr Zelensky to investigate his political rival, former Vice President Joe Biden, in a July phone call.

In that call, Trump pressed the Ukrainian president to investigate possible Ukraine involvement in the 2016 election email hacking.

What did the RNC know?

The Gates interview notes also suggest that the Republican National Committee (RNC) has more knowledge than previously disclosed about the hacked DNC emails.

Gates told investigators the RNC had "non-public information" about the timing of the release of the emails on WikiLeaks but did not identify who at the RNC knew this information. The RNC says it "had no advanced knowledge" of the releases.

WikiLeaks founder Julian Assange was charged with conspiracy to commit computer intrusion by the U.S. government in April.

BuzzFeed and CNN filed a Freedom of Information Act request seeking all documents related to the investigation by former FBI director Mueller and a lawsuit to get access to the papers. Another installment will be released every month for at least the next eight years, according to Buzzfeed.

(With input from Reuters)