In a news conference in the Jordanian capital of Amman, Hijab said he defected last week from the government and joined the 17-month Syrian uprising of his own will. He said he was not dismissed from his post as Syrian authorities claimed and urged other Syrian leaders to break from the government.
Hijab said the Assad government currently controls only 30 percent of the nation and is collapsing morally, economically and militarily.The former prime minister is the highest-ranking political figure to defect from the Syrian government. He fled to Jordan with his family.
US considers multiple options
Meanwhile, U.S. Secretary of Defense Leon Panetta says he is confident the United States could enforce a no-fly zone over Syria, but that a "major policy decision" needed to authorize such a mission has not been made.
Panetta told the Associated Press the United States is considering multiple options for Syria and indicated a no-fly zone is not a top priority.
"We have planned for a number of contingencies that could take place and one of those possible contingencies is developing a no-fly zone. But we've also pointed out difficulties in being able to implement that," he said. "It's not on the front burner as far as I know."
Last year, the U.S. and its NATO allies implemented a no-fly zone over Libya as rebels fought against and eventually ousted leader Moammar Gadhafi.
But the circumstances are different in Syria, which has much more sophisticated air defenses than Libya.
Syrian President Assad's forces have increased air attacks in recent weeks, targeting rebel strongholds in key places such as the nation's largest city of Aleppo.
Syrian rebels have said they need a no-fly zone to protect against the attacks.
Diplomatic efforts
Foreign ministers of the Organization of Islamic Cooperation will be holding a summit in Mecca late Tuesday night, after agreeing to recommend suspending Syria from the group.
The move by the 57-member OIC could lead to a diplomatic dispute during the summit between Syrian ally Iran and pro-opposition Saudi Arabia.
Also Tuesday, United Nations humanitarian chief Valerie Amos begins a three-day visit to Syria and Lebanon to discuss ways to urgently boost relief efforts to civilians caught in the conflict.
A U.N. statement Monday said the visit is aimed at drawing attention to the deteriorating humanitarian situation in Syria, and the impact on people still in the country and those who have fled to other countries, including Lebanon.
"The humanitarian situation in Syria has further worsened in recent weeks as fighting has spread in Damascus and to Aleppo and other cities," the statement said. "Two million people are now estimated to have been affected by the crisis and over one million have been internally displaced."
In China, the foreign minister is scheduled to hold talks with a special envoy to President Assad. China says it is also considering inviting opposition members to visit.
China has joined Russia in vetoing three United Nations Security Council resolutions threatening Syria with sanctions for using heavy weapons against civilians.
Violence continues
Fighting continued in northern Syria Tuesday after rebels circulated a video Monday of what they claim is the downing of a Syrian plane and the captured pilot. The rebel video cannot be independently verified.
Opposition activists posted amateur video on YouTube Monday showing a fighter jet flying through the sound of heavy fire, erupting in a ball of flames and trailing a line of smoke. Someone off-camera celebrates, saying the plane had been hit in the town of Mohassen in Deir Ezzor province. Later, video was released of a man, identified as the pilot, surrounded by armed men.
State media say a pilot ejected Monday after suffering technical problems during a "routine training mission" in eastern Syria, and that authorities are searching for him.
According to eyewitness reports, the Syrian government has been using fighter jets as part of its most recent assaults on rebel-held areas across the country.
On Tuesday, the Britain-based Syrian Observatory for Human Rights reported government shelling in Idlib province that it said killed four people. The Observatory said clashes between government forces and rebels were taking place in other areas of the province following rebel attacks on military targets.
The group says more than 20,000 people have been killed since the nation's uprising began in March of last year.
Some information for this report was provided by AP, AFP and Reuters


