Almost a quarter of a million Israelis rallied in central Tel Aviv on Saturday, police said, for a mass protest aimed at pushing the government into reforms to ease the cost of living.

The organizers appeared to have achieved their target of drawing a "critical mass" out onto the streets to underline the staying power of a movement which began in mid-July over housing costs.

Security forces on Saturday arrested prominent opposition figure and former political prisoner Walid al-Bunni and his two sons, Syrian Observatory for Human Rights chief Rami Abdel Rahman said.

The arrests came after Syria vowed on Saturday to hold "free and transparent" elections by the end of 2011 as Arab states in the Gulf joined a chorus of Western pressure over its deadly suppression of anti-regime protests.

Rebel commanders said their fighters captured the town of Bir Ghanam, 80 kilometers south of the Libyan capital, on Saturday.

An Agence France Presse correspondent, although he did not visit Bir Ghanam, was with the several hundred fighters as they advanced north on a road strewn with burned-out vehicles of the Libyan army, some with bodies of dead soldiers inside.

Foreign Minister Walid Muallem said on Saturday that elections to a new parliament will be held by year's end, as Syria's regime faces international pressure over its deadly crackdown on protests.

"Syria will hold free and transparent elections that will give birth to a parliament representing the aspirations of the Syrian people," Muallem said in a meeting with foreign ambassadors posted to Damascus.

Syria's President Bashar Assad has no future in politics, German Foreign Minister Guido Westerwelle said in an interview to be published Sunday.

"I don't believe that Assad has a political future ahead of him which is supported by the Syrian people", Westerwelle told the German Sunday newspaper Allgemeine Sonntagszeitung.

Gulf Arab states on Saturday turned up the heat on Damascus, joining a growing chorus of pressure after Syrian security forces shot dead at least 22 people as tens of thousands staged anti-regime protests.

The six-member Gulf Cooperation Council called for an "immediate end to violence... and bloodshed."

The State Department on Friday urged Americans in Syria to leave the country immediately and advised those who remain in the country to restrict their movements, as the Syrian government intensified a violent crackdown on opposition protesters.

The warning came as congressional calls grew for the Obama administration to impose severe new sanctions on President Bashar Assad's regime.

Iran's Foreign Minister Ali Akbar Salehi hopes that the trial of two U.S. citizens detained in the Islamic republic on espionage charges will lead to their freedom, local media reported Saturday.

"We hope that the trial of these two (U.S.) nationals will proceed in a manner that will result in their freedom," Salehi was quoted as saying by Fars news agency.

Four prisoners and a guard were killed in clashes at a prison in the central Iraqi city of Hilla, during which eight inmates escaped, officials said on Saturday.

The clashes, in which nine people were also wounded, broke out after a prisoner seized a rifle from a guard and killed him, said Mohammed Ali al-Massudi, the governor of Babil province, of which Hilla is the capital.

Activists said Saturday that at least 24 Syrian civilians have been killed as security forces fired on anti-government protesters as part of a nationwide crackdown.

Syria-based rights activist Mustafa Osso said most of the deaths occurred in Damascus suburbs during daytime Friday protests and late night demonstrations following evening Ramadan prayers.