TRIPOLI/WASHINGTON: The top White House anti-terror official John Brennan pressed Libyan leaders Wednesday to hunt down those guilty of killing Ambassador Chris Stevens and three other Americans as controversy mounted in Washington.

The former commander of a Tripoli special security team told U.S. lawmakers at a hearing into Steven’s death that Al-Qaeda’s presence in Libya is growing every day.

Security was tight in the Libyan capital for Brennan’s talks with national assembly chief Mohammad Megaryef, Libya’s de facto head of state, and other senior officials.

Brennan set out to Megaryef “specific additional steps Libya can take to better assist the U.S. in ensuring that the perpetrators are brought to justice,” the White House said.

“Mr. Brennan encouraged Libyan officials to move quickly on refining their policies and advancing government capabilities in the security and justice sectors,” National Security Council spokesman Tommy Vietor said.

The day after the assault, the Libyan authorities promised their full cooperation with a U.S. inquiry into the attack but security conditions in Benghazi have meant that it was only on Oct. 4 that an FBI team probing the killings was finally able to visit the scene.

Brennan also urged Libya to “take full and timely advantage of specific offers of assistance from the United States and other international partners.”

The envoy’s visit came with political temperatures rising in Washington as senior State Department officials gave evidence to a congressional hearing into the deadly consulate attack.

The Al-Qaeda “presence grows every day. They are certainly more established than we are,” Lieutenant Colonel Andrew Wood, who headed a 16-strong security team in Tripoli, said.

He was addressing a hearing of the congressional House Oversight and Government Reform committee into the Sept. 11 attack.

In Benghazi, “the situation remained uncertain and reports from some Libyans indicated it was getting worse. Diplomatic security remained weak,” Wood said.

Wood said he had come forward as a private citizen to reveal what he knew about the situation in Libya from the time he spent as commander of a 16-strong site security team based in Tripoli from mid-February to mid-August.

He visited Benghazi twice and was there in June when the British ambassador’s convoy was attacked and had helped provide medical and security help afterward.

Wood said: “The security in Benghazi was a struggle and remained a struggle throughout my time there.

“Fighting between militias was still common when I departed. Some militias appeared to be degenerating into organizations resembling freelance criminal operations” he said, in prepared remarks.

“Targeted attacks against Westerners were on the increase,” Wood said, adding that in June there had been a direct threat made against Stevens on Facebook, mentioning that he liked to jog regularly.

In a dramatic account Tuesday, two State Department officials described a relentless attack in which dozens of armed men invaded the U.S. consulate in Benghazi, setting it on fire and hunting through the building for staff.

There had been no warning that an attack was planned, and in the hours before the streets outside the compound had been calm, they said on a conference call with reporters, asking to remain anonymous.

The new account contradicts initial reports by State Department officials which said it was a “spontaneous” attack sparked by a protest against an anti-Islam film.

Benghazi was the cradle of the 2011 revolt that toppled and killed long-time dictator Moammar Gadhafi but has since become the focus of mounting violence, some of it involving Islamist or even jihadist militias.