Representative Darrell Issa
Representative Darrell IssaAFP/Getty Images/File

U.S. officials refused calls for more security at its Benghazi consulate despite attacks on Western targets in the city in the weeks before the attack on the mission, top Republicans charged Tuesday.

The U.S. mission in Libya had made "repeated requests for increased security" but they were ignored by Washington, Representative Darrell Issa, chairman of the House Oversight and Government Reform Committee, said, according to AFP.

Amid mounting questions over how the U.S. mission in Benghazi came under attack on September 11 leading to the deaths of four Americans, Issa said he would call an October 10 hearing of his watchdog committee to seek answers.

In a letter to Secretary of State Hillary Clinton, he detailed a series of attacks on U.S. personnel and other Westerners in the months leading up to the assault, in which ambassador Chris Stevens and three others died.

"Multiple U.S. federal government officials have confirmed to the committee that, prior to the September 11 attack, the U.S. mission in Libya made repeated requests for increased security in Benghazi," Issa said in his letter, quoted by AFP.

"The mission in Libya, however, was denied these resources in Washington," he declared, the message co-signed by Republican congressman Jason Chaffetz.

They highlighted about a dozen other security incidents in the city, including in April when a small homemade device was thrown over the consulate's fence and a June 6 bomb attack when a hole was blown in the north gate.

They also demanded to know what measures had been taken to boost security and a detailed list of any requests by the U.S. embassy in Tripoli for extra security and the department's response.

In her reply to Issa, Clinton vowed to work with Congress to shed light on what happened, urged the Congressman to await the results of a board of inquiry she had already convened under a panel chose by her office.

She argued this would give the "result we both want: a full and accurate accounting of the events and a path forward to prevent them happening again."

And she cautioned that lawmakers should "withhold any final conclusions about the Benghazi attack until the committee can review the findings."

Clinton has launched an internal review into whether there were any security lapses at the consulate, while the FBI and the Libyan authorities are carrying out separate investigations into the attack.

Clinton said the State Department would answer "specific questions in your letter... as expeditiously as possible, while taking into account any measures to protect classified information."

Three weeks after the deadly assault, Libyan authorities said Tuesday that an FBI team in the country has now been approved to visit Benghazi, but details of its cooperation still need to be ironed out.

"We are getting ready for the FBI team to go to Benghazi and meet with our team, start joint investigations... and visit the place where it happened," said Deputy Foreign Minister Mohammed Abdel Aziz, according to AFP.

Acting Assistant Secretary Beth Jones met Tuesday with Libyan officials in Tripoli to discuss the investigation, the report said.

On Tuesday it was reported that the U.S. is prepping the elite military commandos of the Joint Special Operations for a possible mission to find, capture or kill the suspected terrorists who carried out the attack on the Benghazi mission.

Senior military and counterterrorism officials said that Washington is preparing "target packages" and detailed information of the suspects, knowledge of the area and attack plans in anticipation of any order from President Obama to carry out action against those determined to be responsible for the violence and murders.

U.S. President Barack Obama admitted last week that the attack was clearly more than a "mob action.”

Libyan leader Mohammed Magariaf said last week the attack was not related to the anti-Islam film that is being used as an excuse for violent protests in many countries.