US president Barack Obama looks on as he speaks to service members at the Naval Station Rota, in Rota, southwestern Spain on July 10, 2016.

US President Barack Obama warns about the “not perfect” cybersecurity in the government, saying more has to be done.

“I am concerned about it. I don’t think we have it perfect. We have to do better, we have to learn from mistakes,” Obama said at a news conference in Madrid on Sunday. “We know that we have had hackers in the White House.”

Obama made the remarks in the wake of an FBI investigation into use of private email server by Democratic presumed nominee Hillary Clinton, while serving as secretary of state in the first Obama administration.

US Democratic presidential candidate Hillary Clinton speaks during a event in Atlantic City, New Jersey, on July 6, 2016.

According to FBI Director James Comey, it was “possible” that hackers accessed her account, but “given the nature of the system and the actors potentially involved, we assess we would be unlikely to see such direct evidence.”

After Comey called her “extremely careless” for the measure and the US State Department announced it was launching an internal investigation, Clinton admitted that she had made a “mistake.”

“It was a mistake for me to use personal email. And I regret that. I am certainly relieved and glad that the investigation has concluded but I also know how important it is to make sure everybody understands that I would certainly not do that again,” Clinton said in an interview with CNN on Friday.

She had previously claimed that she “never sent or received” classified data.

“Although we did not find clear evidence that Secretary Clinton or her colleagues intended to violate laws governing the handling of classified information, there is evidence that they were extremely careless,” said FBI director after the investigation wrapped up.

FBI Director James Comey testifies during a hearing before House Oversight and Government Reform Committee July 7, 2016 on Capitol Hill in Washington, DC.

In the interview, Clinton toned down her previous allegation, saying “I certainty did not believe that I received or sent any material that was classified.”

The issue has been used mostly by the Republicans as a means to topple the former First Lady in the run-up to the 2016 presidential election.

The Republican National Committee reacted to her remarks, accusing her of no telling the truth to the American nation.

“Even now, Hillary Clinton is unwilling to tell the American people the truth about her illicit email server that broke the rules and put national security at risk,” RNC spokesman Michael Short said in a statement. “The only thing Hillary Clinton seems to be clarifying is that she is determined to continue misleading voters and obfuscating the facts about her reckless conduct as secretary of state.”