Syria on Thursday released 552 people who were detained over their involvement in political unrest and who have "no blood on their hands," the official SANA news agency reported.

The news agency said that "552 prisoners involved in the latest events in Syria and who have no blood on their hands were released."

Former Israeli Prime Minister Ehud Olmert was on Thursday indicted alongside a number of other people for allegedly taking bribes in a massive property scandal, judicial sources said.

The allegations stem from Olmert's tenure as Jerusalem mayor and will add to the woes of the former premier, who is already on trial on three unrelated counts of fraud and bribery.

A spate of attacks against Shiite pilgrims and neighborhoods in Iraq killed at least 53 people on Thursday as the country grapples with a weeks-long political row that has stoked sectarian tensions.

The violence, which wounded more than 100, was the worst since attacks killed 60 people across Baghdad on December 22, soon after the crisis erupted when Vice President Tareq al-Hashemi was charged with running a hit squad, and following the U.S. troop pullout.

France on Thursday urged the Arab League to strengthen its monitoring mission in Syria amid concerns its observers have failed to stem bloodletting in the country.

The French foreign ministry's deputy spokesman, Romain Nadal, also called on the Arab grouping to accept help in organizing the mission, in particular from the United Nations.

France's foreign minister on Wednesday warned Arab observers trying to assess Syria's implementation of a peace agreement not to let themselves be manipulated by the regime of President Bashar al-Assad.

"The Arab League can take credit for taking an initiative but the Arab League observers must not let themselves be manipulated by the regime, as the regime is trying to," Alain Juppe said after talks with his Portuguese counterpart Paulo Portas.

Israelis and Palestinians were downbeat about peace prospects on Wednesday, a day after the two sides held their first face-to-face talks since September 2010 at a meeting in Amman.

"It's difficult to be optimistic because (Palestinian President Mahmoud) Abbas continues to insist that Israel must commit to the 1967 lines and a settlement freeze, failing which he threatens tough measures," Israeli lawmaker Benny Begin told public radio.

Syria accused the United States on Wednesday of interfering in Arab League affairs, as a U.S. envoy traveled to Cairo for talks with the bloc about ending the Damascus regime's deadly crackdown on dissent.

Meanwhile, democracy activists have denounced the 22-member Arab bloc over the "unprofessionalism" of a team of peace observers whose presence in Syria has failed to stem the bloodshed.

Syria's opposition was in disarray Wednesday, struggling to present a united front in the face of a protest crackdown whose death toll rose again despite the presence of Arab League monitors.

Western powers have repeatedly called on the Syrian opposition to put aside differences and join forces in their bid to oust President Bashar Assad and his autocratic regime after more than nine months of bloody violence.

Armed Islamists on Wednesday attacked a hotel in Aden that they suspected of hosting prostitutes and set it on fire, causing the death of two who tried to escape from windows, Yemeni police said.

The gunmen opened fire on workers at the Layali Dubai (Dubai Nights) hotel, in the Sanafir neighborhood in the southern city, "before they set the hotel on fire, causing the death of two and injuring 15 guests," a police official told Agence France Presse.

Bomb and grenade attacks north of Baghdad on Wednesday killed three people -- two children and a policeman -- and wounded 17 other people, officials said.

A series of 11 apparently coordinated blasts targeting security officers rocked the restive central city of Baquba, 60 kilometers north of Baghdad, on Wednesday morning, an official in the provincial security command center and a doctor at the city's hospital said.