TRIPOLI, LIBYA: US President Barack Obama’s anti-terror adviser, John Brennan, was in Tripoli yesterday to discuss investigations into a deadly attack on US diplomats in Libya last month, an official said.

Tripoli tightened security as Brennan headed into meetings with Muhammad Megaryef, president of the Libyan national assembly, as well as foreign and interior ministry officials, said the Libyan official.

His visit comes almost one month after the Sept. 11, 2012 attack on the US mission in the eastern city of Benghazi in which four Americans, including ambassador Chris Stevens, were killed. It follows the first visit by FBI agents to the crime scene in the eastern city of Benghazi, cradle of the 2011 revolt that toppled and killed long-time dictator Muammar Qaddafi.

The Obama administration has come under fire from Republican foes for the contradictory reports which have come out about the attack, amid allegations of security failures.

In Washington, State Department officials faced a grilling yesterday at a congressional hearing into the Benghazi assault, which has become fodder for the US presidential campaign.

Four US officials will brief lawmakers at the hastily-arranged hearing of the Oversight and Government Reform committee — the main watchdog in the Republican-controlled House of Representatives.

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