Halki, born in 1964, is from the southern province of Deraa where the uprising against  Assad’s  rule erupted, replacing caretaker premier Omar Ghalawanji who was appointed hours after Hijab’s defection.

Like Hijab, Halki who belongs to Syria’s Sunni Muslim majority defected on Monday after only two month in office. Hijab fled to Jordan with his family.

The White House said the defection of Syrian Prime Minister Riyad Hijab shows that President Bashar al Assad’s government is “crumbling from within.”

Moreover, several Syrian diplomats have defected from Assad’s government in the recent weeks, including the ambassador to Iraq, the ambassador to UAE, the charge d’affaires in the UK where his first posting was in Greece as consul from 2003 to 2008, and the charge d’affaires in Cyprus.

The latest development came as battle raged between regime forces and armed rebels in the northern city of Aleppo. The rebel Free Syrian Army on Thursday pulled out completely from the embattled district of Salaheddin, in the northern city of Aleppo, a rebel commander said.

“We have staged a tactical withdrawal from Salaheddin. The district is completely empty of rebel fighters. Regime forces are now advancing into Salaheddin,” said Hossam Abu Mohammed, a Free Syrian Army (FSA) commander, according to AFP. 

“The fighters are withdrawing to Sukari district, where they are preparing a counter-attack,” he told AFP by telephone.

Day two of the most significant ground attack in Aleppo came as Syria’s key regional ally Iran prepared to host a meeting aimed at finding ways to end the ongoing conflict.

“President Assad issued a decree asking Riyad Hijab to form a new government,” SANA TV reported without giving any further details of what the government reshuffle would entail.

Wednesday’s appointment comes after a new parliament was voted in on May 7 in elections boycotted by opposition groups and Western countries as a farce.

Hijab replaces Adel Safar, who was appointed in April last year shortly after a popular uprising erupted in Deraa and later spread acroos the country resulting in a 15-month conflict that still hasn’t come to an end, Al Jazeera reports. A member of the ruling Baath Party, Hijab was minister in the previous cabinet.

The diplomatic maneuvering comes as the Syrian government has agreed to let the UN an other international organizations to send aid workers and supplies to four hard-hit provinces as Bashar al-Assad declares western diplomats personae non gratae.

The ambassadors of the US, Turkey, U.K, France, among others, were declared unwelcome in the country. Also Canada, Italy, Spain and various embassy staff members from Belgium, Bulgaria and Germany were also expelled.

Meanwhile, during a meeting in Beijing on Tuesday, Chinese President Hu Jintao and Russian President Vladimir Putin vowed to increase their cooperation at the U.N. Security Council, where both countries have vetoed resolutions against the Assad regime. Russia later called for an international meeting on the Syrian crisis that would include Iran and Turkey, according to Reuters. 

Heavy clashes between the military and opposition forces in places such as Homs and Latakia were reported today, according to the Syrian Observatory for Human Rigths.

According to figures of the Britain-based Syrian Observatory for Human Rights, more than 13,500 people, mostly civilians, have lost their lives in the uprising.