Egypt's presidential race kicked off on Saturday, with registration open for candidates to run the country after a popular uprising ousted veteran president Hosni Mubarak last year.

Hopefuls must be endorsed by at least 30 members of parliament or 30,000 eligible voters for the landmark election on May 23.

Air strikes that residents said were carried out by U.S. warplanes killed 27 suspected al-Qaida militants in mountains south of the Yemeni capital, local officials said on Saturday.

"They were new recruits, youths from the region, taken by surprise by the raids which struck as they were dining in training camps" on Friday night, one official said, on condition of anonymity.

Israeli air strikes on Gaza killed 15 Palestinians, including a militant group chief, medics said on Saturday, in the deadliest 24 hours in the border area in more than three years.

A Palestinian riding a motorcycle was killed and two others were wounded in an Israeli air raid close to the southern town of Rafah near the border with Egypt on Saturday afternoon, Palestinian medics said.

Around 100 protesters calling for an end to military rule in Egypt clashed with soldiers near the U.S. embassy in Cairo, an Agence France Presse correspondent reported.

Shouting "Down with military power!" the protesters lobbed stones at the soldiers, who responded by throwing them back and trying to disperse the crowd.

Saudi authorities have ordered a probe after more than 50 women students were hurt when security forces dispersed a campus protest this week, media and a local official said on Friday.

On Wednesday members of the religious police and law enforcement officers used water cannons to break up a sit-in by women students at the Abha University in the south of Saudi Arabia, the Sebaq news website reported.

Tens of thousands of Bahrainis flooded the streets of the capital Manama on Friday demanding political reforms, a year after authorities crushed an uprising, an activist said.

Policemen fired tear gas at a group of protesters but the rallies were largely peaceful and no one was arrested, said Nabil Rajab, an activist who heads the Bahraini Center for Human Rights.

U.N. humanitarian aid chief Valerie Amos said on Friday that Syria had agreed to allow a preliminary assessment of the relief needs in areas hard hit by the year-old conflict.

Amos, who has toured the battered city of Homs and refugee camps in Turkey this week, also said Damascus must allow aid groups "unhindered access to evacuate the wounded and deliver desperately needed supplies".

Investigators probing violations during Libya's conflict said Friday they are giving the U.N.'s human rights chief a list of people who should face international or national justice.

The commission of inquiry also called for further probes into NATO air strikes on Libya, saying it was unable to tell if the alliance took adequate precautions to protect civilians in some of its attacks.

Saudi Arabia must "release immediately and unconditionally six Saudis" held for nearly a year in connection with a protest that only one of them attended, Amnesty International said on Friday.

The London-based rights group said five of the men were being held without trial in connection with Saudi Arabia's "Day of Rage" protest which was planned for March 11, 2011.

Four generals who had defected from the Syrian army arrived in Turkey Friday, Anatolia news agency reported, citing local Turkish sources.

The four were among some 10 high-ranking army officers stationed in cities including Damascus, Homs and Latakia, who crossed the border into Turkey's southern province of Hatay to join the Syrian rebels, the state-run Turkish agency said.