A hacking group that appears to be linked to the Iranian government attempted to break into US President Donald Trump's re-election campaign but were unsuccessful, sources familiar with the operation told Reuters on Friday. Microsoft Corp said earlier on Friday that it saw "significant" cyber activity by the group which also targeted current and former US government officials, journalists covering global politics and prominent Iranians living outside Iran, the company said in a blog post http://bit.ly/2ngs5bZ.

Republican Trump's official campaign website is the only one of the remaining major contenders' sites that is linked to Microsoft's cloud email service, according to an inspection of publicly available mail exchanger records. The Trump campaign's Director of Communications Tim Murtaugh said, "We have no indication that any of our campaign infrastructure was targeted."

In a 30-day period between August and September, the group, dubbed "Phosphorous" by the company, made more than 2,700 attempts to identify consumer email accounts belonging to specific customers and then attacked 241 of those accounts. "Four accounts were compromised as a result of these attempts; these four accounts were not associated with the US presidential campaign or current and former US government officials," the blog post said. "Microsoft has notified the customers related to these investigations and threats and has worked as requested with those whose accounts were compromised to secure them."

Microsoft's blog post did not identify the election campaign whose network was targeted by Phosphorous hackers. Nineteen Democrats are seeking their party's nomination to run for president in the November 2020 election. Three Republicans have announced their candidacy to challenge Trump in the party's nominating contest. Hacking to interfere in elections has become a concern for governments, especially since U.S intelligence agencies concluded that Russia ran a hacking and propaganda operation to disrupt the American democratic process in 2016 to help then-candidate Trump become president. Moscow has denied any meddling.