Washington: Central Intelligence Agency (CIA) director David Petraeus on Friday resigned over an extramarital affair, saying his behaviour was “unacceptable”.

The top intelligence official of the US submitted his resignation to US President Barack Obama during a meeting at the White House.

“After being married for over 37 years, I showed extremely poor judgement by engaging in an extramarital affair. Such behaviour is unacceptable, both as a husband and as the leader of an organisation such as ours,” he said in a statement, according to CNN.

Obama accepted his resignation and praised Petraeus on his extraordinary service.

“I am completely confident that the CIA will continue to thrive and carry out its essential mission, and I have the utmost confidence in Acting Director Michael Morell and the men and women of the CIA who work every day to keep our nation safe,” he said

“David Petraeus has provided extraordinary service to the United States for decades. By any measure, he was one of the outstanding General officers of his generation, helping our military adapt to new challenges, and leading our men and women in uniform through a remarkable period of service in Iraq and Afghanistan, where he helped our nation put those wars on a path to a responsible end,” he said.

“By any measure, through his lifetime of service David Petraeus has made our country safer and stronger,” Petraeus said.

Meanwhile, news reports said Petraeus extramarital affair was revealed over the course of an FBI investigation.

“The FBI had been investigating an unrelated and much broader case before stumbling on the affair,” Fox News reported.

“FBI during the course of this investigation, the name of biographer Paula Broadwell came up. FBI followed that lead and in doing so, uncovered his affair with her. The FBI for some time was concerned that perhaps Petraeus was some sort of victim, but there has been no evidence discovered to back up such concerns,” the news channel said.

Before joining the CIA, Petraeus successfully headed the US Army operations in both Iraq and Afghanistan.

“Dave’s decision to step down represents the loss of one of our nation’s most respected public servants. From his long, illustrious Army career to his leadership at the helm of CIA, Dave has redefined what it means to serve and sacrifice for one’s country,” James Clapper, the director of National Intelligence, said.

“Since he took over as Director in September of last year, he and I have worked together to tackle some of the most challenging issues faced by the Intelligence Community in more than a decade,” he said.

“Whether he was in uniform leading our nation’s troops in Iraq and Afghanistan, or at CIA headquarters leading the effort to generate intelligence used to keep our nation safe, Dave inspired people who had the privilege of working with him,” Clapper said.

Regretting the resignation of David Petraeus as director of the CIA, Senator Dianne Feinstein, the chairman of the Senate Intelligence Committee, said this is an enormous loss for the nation’s intelligence community.

“Director Petraeus is an individual who has devoted nearly 40 years of service to his country, rising through the ranks to become a distinguished four-star general and commander of American forces in Iraq and Afghanistan,” she said.

“I wish President Obama had not accepted this resignation, but I understand and respect the decision. David Petraeus is one of America’s best and brightest, and all Americans should be grateful for his service. Deputy Director Michael Morell will serve as acting director, so I am confident the agency is in very good hands until the president selects a replacement,” Feinstein said.

Republican Senator, John McCain, said that Petraeus will stand in the ranks of America’s greatest military heroes.

“His inspirational leadership and his genius were directly responsible – after years of failure – for the success of the surge in Iraq,” he said.