A data program used by the campaign of the Democratic presidential candidate, Hillary Clinton, was “accessed” as a part of hack on the Democratic National Committee (DNC) that intelligence officials believe was carried out by Russia’s intelligence services, Clinton’s campaign said on Friday.

The news came as a new Reuters-Ipsos poll, released after Clinton’s acceptance of the Democratic nomination for president at the party’s convention in Philadelphia, put her six points ahead of her Republican rival, Donald Trump.

Hacks against the Democratic party, revealed in the past week, have been blamed on Russian intelligence services. The Clinton campaign has accused the Trump campaign of involvement.

Clinton spokesman Nick Merrill said that despite the breach of the campaign network, “no evidence” had been found to suggest that the “internal systems have been compromised”. Reuters, citing people familiar with the matter, first reported that the Clinton computer network had been hacked.

In a statement, Merrill said: “An analytics data program maintained by the DNC, and used by our campaign and a number of other entities, was accessed as part of the DNC hack.

“Our campaign computer system has been under review by outside cyber security experts. To date, they have found no evidence that our internal systems have been compromised.”

The FBI said it “takes seriously any allegations of intrusions” and is “aware of media reporting on cyber intrusions involving multiple political entities, and is working to determine the accuracy, nature and scope of these matters”.

An analytics data program maintained by the DNC, and used by our campaign and a number of other entities, was accessed
Nick Merrill, Clinton campaign

The Trump campaign has denied claims of involvement in the hacks. On Friday, senior communications adviser Jason Miller said in a statement: “This seems to be a problem wherever Hillary Clinton goes. Hopefully this time there wasn’t classified or top secret information that puts American lives at risk.”

Russian hackers, designated Cozy Bear and Fancy Bear by cybersecurity analysts, broke into the Democratic National Committee at the beginning of last year and are believed to be the source of anti-secrecy organization WikiLeaks’ release of 20,000 emails last week, though the group has denied this.

Last Sunday, that leak led to the resignation of the DNC chair, Debbie Wasserman Schultz, on the eve of the Democratic national convention in Philadelphia.

The emails revealed exchanges between party officials discussing ways to undermine Vermont senator Bernie Sanders, and were seized upon by Sanders supporters who had long called for Wasserman Schultz’s resignation, charging the DNC with tipping the scales in Clinton’s favor.

The breach of the DNC is believed by security researchers in private industry and the US government to have been the work of Russian intelligence services.

This week the fundraising network of the the Democratic Congressional Campaign Committee (DCCC) was also breached, an act Reuters said US intelligence officials had attributed to Russians as well.

The US Department of Justice’s national security division is investigating whether hacking attacks on Democratic political organizations threatened US security, sources familiar with the matter said.

The involvement of the justice department’s national security division was a sign that the Obama administration has concluded that the hacking was state-sponsored, individuals with knowledge of the investigation said.

Earlier, the Clinton campaign, based in Brooklyn, referred to a comment from earlier this week by campaign senior policy adviser Jake Sullivan, criticizing Trump and calling the hacking “a national security issue”.

Clinton’s campaign has said that the Russians hacked the DNC emails and released them to sow discord in the party and, ultimately, help Trump. The Trump campaign has denied this. Trump himself said a controversial call on Wednesday for Russia to find and release 30,000 “missing” emails from Clinton’s time as secretary of state was “sarcastic”.

Amongst the fallout from the scandal and the Democratic convention, the Reuters-Ipsos poll released on Friday showed nearly 41% of likely voters favoring Clinton, 35% favoring Trump, and 25% picking “other”. The poll had a credibility interval of four percentage points.

On Friday, the Department of Justice had no comment about the reported hack of the Clinton campaign. It was not immediately clear what if any information on the campaign’s computer system hackers might have been able to access.

In the DCCC breach, hackers gained access to the entire network, people familiar with the matter told Reuters, detailing the extent of the breach for the first time. Access to the full network would have given access to everything from emails to strategy memos and opposition research prepared to support Democratic candidates in campaigns for the House.

The hack of the DCCC, which is based in Washington, was reported first by Reuters on Thursday, ahead of Clinton’s convention speech in Philadelphia. Russian officials could not be immediately reached for comment. The DCCC said in a statement early on Friday that it has hired the cybersecurity firm CrowdStrike to investigate.

“We have taken and are continuing to take steps to enhance the security of our network,” the DCCC said. “We are cooperating with federal law enforcement with respect to their ongoing investigation.”