A typo in an email from one of Hillary Clinton's aides may have been responsible for allowing Russian hackers to access tens of thousands of emails belonging to top staffers.

Clinton's campaign chairman John Podesta became the victim of a cyber attack when hackers gained access to his emails after he saw a warning message in his inbox back in March claiming to be from Google.

The email told him he needed to change his password immediately because someone had tried to access his account.

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A typo in an email from one of Hillary Clinton's aides may have been responsible for allowing Russian hackers to access tens of thousands of emails belonging to top staffers. Charles Delavan, seen right, wrote that a phishing email was 'legitimate' instead of illegitimate

Delavan is seen right in this group shot with Clinton that was shared to Facebook

One of Podesta's aides forwarded the email to computer technician Charles Delavan to check whether the message was legitimate.

'This is a legitimate email,' Delavan responded in an email . 'John needs to change his password immediately.'

But Delavan told the New York Times in a story published Tuesday that the email contained a critical spelling mistake and he had meant to type the word 'illegitimate' instead of 'legitimate'.

He said he knew it was a phishing attack and Delavan told the Times it was a mistake that has plagued him since. The Times traced Delavan's email in an analysis of how the hacking scandal unfolded.

Campaign chairman John Podesta became the victim of a cyber attack when he was sent an email claiming to be from Google in March saying he needed to change his password

One of Podesta's aides forwarded the email to computer technician Charles Delavan to check whether the message was legitimate

The email claimed to be from Google and told him he needed to change his password immediately because someone had tried to access his account

Hackers were able to gain access to thousands of Podesta's emails, which were then leaked by WikiLeaks towards the end of Clinton's presidential campaign.

U.S. intelligence officials have since accused Russia of hacking into Democratic officials' email accounts in an attempt to interfere with the presidential campaign.

The CIA concluded that Russia aimed specifically to help Trump win the presidency, according to a report in the Washington Post.

Trump hit out at the CIA claims labeling them 'ridiculous' during an interview with Fox News Sunday.

'I think it's ridiculous. I think it's just another excuse. I don't believe it,' Trump said.

'I don't know why and I think it's just - you know, they talked about all sorts of things. Every week it's another excuse.'

Donald Trump dismissed CIA claims that Russian hacks were intended to help him win the election as 'ridiculous', also claiming that Democrats were pushing the reports in the media