Attackers may have tricked their way in behind protesters in Libya

The militiamen who attacked the US consulate in Benghazi may have tricked their way in behind unarmed protesters who were demanding to deliver a letter complaining about a US-made film mocking Islam, according to a senior official.

Sources on the ground told the official that security guards opened the gate to petitioners during the demonstration on Tuesday evening and were then overwhelmed by dozens of combatants.

Separately, a Libyan deputy interior minister said the attackers may have had inside help from members of the security forces working on the site.

Wanis el-Sharef said that the armed militants used the protest against the film as "cover" for a carefully planned attack that claimed the lives of four Americans, including Chris Stevens, an ambassador.

The attackers raided a safe house in the compound just as US and Libyan security arrived to evacuate staff in the middle of a gun battle, suggesting they may have possessed information about its location.

The senior official concurred with other accounts that the demonstrators and armed attackers formed a crowd of 200 or more.

"There were people who said we have a letter to deliver to the ambassador and got in like that. As far as I understand they were part of the plan," he said.

"I am not saying the Americans were responsible, but did they take the necessary measures or calculate properly what was happening? Because we have seen many, many signs that something was going to happen in Benghazi," he added, referring to several attacks on Western targets by Islamist groups earlier in the summer.

The official admitted that the Libyans and Americans could have worked together to strengthen security after the previous incidents. The consulate was an "interim facility" with no bullet-proof glass or reinforced doors.

He denied reports, however, that US officials in Libya had received intelligence of an assault 48 hours earlier. The White House said yesterday it had no "actionable intelligence" before the assault.

Every account of what happened after the protest began portrays a terrifying saga. While some assailants stormed the main gates, one witness said that others jumped over the compound's wall.

By some accounts, the first shots were fired from inside the compound, provoking retaliation from outside. Libyan security officers guarding the site pulled back because they were so outnumbered, some said. Between 10 and 15 guards are believed to have been killed later during the assault.