Peace envoy Lakhdar Brahimi said on Thursday the deadly conflict in Syria was getting worse as he arrived on his first official trip aimed at ending nearly 18 months of violence.

"We came to Syria to hold meetings with our Syrian brothers because there is a big crisis, and I think it is getting worse," the official SANA news agency quoted the U.N. and Arab League envoy as saying on arrival at Damascus airport.

Libya has made several arrests over an attack on the U.S. consulate in Benghazi that killed the ambassador and three other U.S. nationals, the deputy interior minister told AFP on Thursday.

"The interior and justice ministries have begun their investigations and evidence gathering and some people have been arrested," Wanis al-Sharef said.

Several hundred Palestinians in the Gaza Strip protested on Thursday against an anti-Muslim film that has sparked deadly riots in Libya and Yemen.

The protest, called by the ruling Hamas government's ministry of religious endowments, comes after two days of demonstrations that have left four U.S. embassy staff including the ambassador dead in Libya and a protester shot dead in Yemen.

Libya has set up an independent judicial committee to probe an attack on the U.S. consulate in Benghazi in which four Americans including the ambassador were killed, a spokesman said on Thursday.

"All measures are being taken. An independent judicial committee has been set up to carry out an inquiry," Abdelmonem al-Horr, spokesman for the Libyan interior ministry's security commission, told AFP.

Egyptian President Mohamed Morsi reiterated during a visit to the EU on Thursday that Syrian President Bashar Assad must step down as "a president that kills his own people is not acceptable."

At a news briefing, Morsi interjected to state "this is completely agreed upon" when European Commission President Jose Manuel Barroso told reporters after talks between the two sides that "we are also adamant that Assad should go."

An Egyptian court on Thursday sentenced former Prime Minister Ahmed Nazif to three years in prison and to pay a fine of nine million Egyptian pounds ($1.5 million) for illegal enrichment.

Nazif, who left his post in late January 2011 at the start of a popular revolt against then President Hosni Mubarak, was accused of abusing his post to make illegal gains, the official MENA news agency reported.

Egypt's Islamist President Mohammed Morsi Thursday slammed "attacks" on the Muslim prophet Mohammed in a film on Islam that sparked an outcry in Egypt, while also stressing that he condemned violence.

"We Egyptians reject any kind of assault or insult against our prophet. I condemn and oppose all who... insult our prophet," Morsi, on an official visit to Brussels, said in remarks broadcast by Egyptian state television.

International peace envoy Lakhdar Brahimi arrived in Syria on Thursday on his first visit to the strife-torn country since his appointment two weeks ago, his spokesman said.

"During his visit to Syria, Brahimi will hold talks with the government and with representatives of the Syrian opposition and civil society," said a statement from Ahmad Fawzi, who had previously announced that the veteran diplomat would meet President Bashar Assad.

British Foreign Secretary William Hague said on Thursday in a visit to the Iraqi capital that Syrian President Bashar Assad's regime is "doomed" and should not survive.

"We believe that the Assad regime is doomed, that it is not possible for it to survive, and so many crimes (have been) committed that it should not survive," Hague said at a joint news conference with Iraqi Foreign Minister Hoshyar Zebari.

Yemeni police Thursday shot dead a protester and wounded five others when they opened fire on a crowd attempting to storm the U.S. embassy in Sanaa to protest a film mocking Islam, a security official said.

The shooting came as protesters, chanting "O, messenger of Allah... O, Mohammed," launched a second charge on the complex which they had stormed earlier but were ejected by the security forces.