Brussels:
European Union (EU) Foreign Policy Chief Catherine Ashton on Wednesday condemned as "despicable" the attack on the US consulate in Benghazi and urged Libya to ensure the protection of diplomats and foreign staff.
"I am deeply shocked by the despicable attack" that claimed the lives of four US officials, including US Ambassador Christopher Stevens, Ms Ashton said in a statement.
"I call on Libya to take all necessary measures without delay to protect the lives of all diplomats and foreign staff" working in the country, she added.
A senior EU diplomat, speaking on condition of anonymity, also stressed "the need for more effective protection of diplomats" in line with the Vienna Convention.
The Americans were killed when Islamists, angered by a US-made film deemed offensive to Islam, late on Tuesday attacked the consulate with rocket-propelled grenades before looting it and torching the building, witnesses said.
European Parliament speaker Martin Schulz, speaking in Strasbourg, also issued a strong condemnation.
"The US diplomat and his staff were in Libya to help the country to return to peace, stability and prosperity," Mr Schulz said.
Both he and Ms Ashton urged the Libyan authorities to find the perpetrators and bring them to justice.