US secret service chief Julia Pierson vowed  that the breach of White House security will not be allowed to happen again, amid mounting criticism over the agency’s failure to prevent the intrusion of a man Sep 19.

Appearing before the House and Government Operations Committee, Pierson said the intrusion by US Army veteran Omar Gonzalez who jumped a fence and made his way deep into the White House, was “unacceptable”. Gonzalez was reported to be armed with a knife, though no one was hurt in the incident and President Barack Obama was not present that time, Xinhua reported.

“I take full responsibility and it will never happen again,” she told lawmakers, who bombarded her with questions and criticism over the secret service’s alarming failure to protect the security of the presidential residence and first family.

Committee chairman Darrell Issa blasted the agency for “a history of misbehaviour, security failure” that has clearly blemished its record, noting that the country spends $1.5 billion on its operations.

“In light of the recent break-in, we have to ask whether the culture at the secret service and possible declining morale have an impact on operations,” Issa said.

He cited another two incidents of White House’s security breach, including a couple’s success in making their way into a White House state dinner in November 2009 without being questioned, and the shooting by a gunman at the White House building Nov 11, 2011, that caused over $100,000 in damages.

Moreover, he mentioned the 2012 scandal which involved 13 secret service agents who solicited prostitution in Colombia while preparing for a visit by President Obama.

Pierson, who took over her position last March, pledged to redouble her efforts to “bring the secret service to a level of performance that lives up to the vital mission we perform, the important individuals we protect, and the American people we serve.”