Vatican City — The Vatican voiced its "firmest possible condemnation" of the fatal attack on the US diplomatic mission in Benghazi, Libya, which killed four Americans including the ambassador to the country.

"Nothing can justify the activity of terrorist organizations and homicidal violence," read the statement issued by Vatican spokesman Fr Federico Lombardi S.J. September 13.

"Along with our sadness, mourning and prayers for the victims, we again express the hope that, despite this latest tragedy, the international community may discover the most favorable ways to continue its commitment in favor of peace in Libya and the entire Middle East."

Ambassador J. Christopher Stevens was killed Tuesday September 11 in a fire started after the U.S. consulate in Benghazi was stormed by violent mobs.

The 52-year-old, who was a native of California, had been a career diplomat with the U.S. Foreign Service since 1991. United States officials are now investigating whether the attack was planned by militant jihadist groups.

The violence was sparked by the posting on YouTube of extracts of a low-budget U.S. film mocking the Prophet Mohammed, the 6-7th century founder of Islam.

According to CNA, similar scenes of unrest have now been witnessed across North Africa and the Middle East, most notably in Yemen and Egypt. In the Yemeni capital of Sanaa September 13 demonstrators stormed the grounds of the US embassy and burned the American flag before being driven back by security forces. Reports of protests are also emerging from Tunisia, Sudan and Morocco.

Meanwhile in Nigeria, a nationwide security alert was issued September 13 to forestall violence over the alleged "blasphemous" film released in the United States, which sparked demonstrations around the world that led to the death of the American ambassador in Libya.

"Following recent violent demonstrations in some parts of the world linked to a recent US film believed to have offended a section of some religious faithful, the police has taken immediate proactive security measures to ensure that no similar violence is replicated within our country," police spokesman Frank Mba said in a statement.

Hours before the police alert was announced, Special Task Force (STF) personnel dispersed a group of people demonstrating against the controversial movie in Jos.