An FBI agent walks past revelers gathered in Times Square on New Year's Eve in New York, U.S. December 31, 2016. REUTERS/Stephanie Keith

WASHINGTON — The FBI alerted the Democratic National Committee as recently as New Year’s Eve that hackers were once again trying to break into their computer systems, BuzzFeed News has learned.

"There was activity the day after the president issued sanctions [against Russia], looking for ways to get into the servers," one high-level source familiar with the investigation said.

A US intelligence officer, who requested anonymity as they were not cleared to speak to the press, said that there have been “multiple attempts” to hack into the DNC since the Nov. 8 elections.

“Many of these attempts are not serious… hackers are trying to re-enter the DNC system but as far as we understand their attempts have not been successful,” said the intelligence officer, who had been in contact with the DNC over the attempts.

Neither offered an explanation for who was behind the intrusion attempts or details about the targeted systems.

Crowdstrike, a private cybersecurity firm hired by the DNC to investigate the original breach that saw thousands of emails of top Democratic Party members hacked and then made public, has also been helping the DNC secure their networks against future cyberattacks.

The Obama administration announced sweeping retaliations against Russian diplomats and intelligence officials on Dec. 29 for what the intelligence community says was a widespread influence operation designed to undermine the US election. The Russian effort included accessing the DNC’s system and using Wikileaks to distribute the contents of sensitive emails, according to US intelligence community analysis. The same day the sanctions were announced, the FBI and Department of Homeland Security issued a public report blaming Moscow for cyberattacks against DNC computer systems as far back as 2015. Those cyberattacks, and the subsequent release of stolen DNC emails, crippled the party on the eve of its June convention and rattled Democratic candidate Hillary Clinton’s presidential prospects through November.

The intelligence community’s analysis says the Kremlin’s influence measures were intended to bolster now President-elect Donald Trump’s run for office.

The ongoing FBI investigation into the DNC server hack came under sharp scrutiny this week when BuzzFeed News revealed the Bureau had never independently accessed or analyzed the committee’s hacked servers. The DNC originally said that was because the FBI never asked; the FBI later said it had asked and been rebuffed by DNC officials.

DNC officials tried to downplay the public disagreement Friday to BuzzFeed News, saying it was likely a miscommunication between the two entities.

The FBI investigation into the cyberattacks is ongoing.