Russian scientific analysis indicated a deadly projectile that hit a suburb of the Syrian city of Aleppo on March 19 contained the nerve agent sarin and was most likely fired by rebels. 

The incident at Khan al-Assal in the northern province of Aleppo killed more than two dozen people. Both the government and rebels have blamed each other for what they say was an attack involving chemical weapons. Both sides also deny using chemical weapons.

Russia, alongside Iran, is Syria’s closest ally and chief arms supplier. The United States cast doubt on the Russian analysis and along with France called for full U.N. access to Syrian sites where chemical weapons use was suspected.

Moscow’s U.N. ambassador, Vitaly Churkin, said Russian experts visited the location where the projectile struck and took their own samples of material from the site. Those samples, he said, were then analyzed at a Russian laboratory certified by the Organization for the Prohibition of Chemical Weapons.

“It was established that on March 19 the rebels launched an unguided Basha’ir-3 projectile towards Khan al-Assal controlled by the government forces,” he said. “The results of the analysis clearly indicate that the ordnance used in Khan al-Assal was not industrially manufactured and was filled with sarin.”

“The projectile involved is not a standard one for chemical use,” Churkin said. “Hexogen, utilized as an opening charge, is not utilized in standard ammunitions. Therefore, there is every reason to believe that it was armed opposition fighters who used the chemical weapons in Khan al-Assal.”

Churkin said he had informed U.N. Secretary-General Ban Ki-moon of the Russian findings. Ban is scheduled to meet Ake Sellstrom, the Swedish scientist heading a U.N. team established to investigate allegations of chemical weapon use in Syria, in New York this week.

The United States has rejected Russian claims raised at the United Nations that Syrian opposition fighters had used chemical weapons.

“We have yet to see any evidence that backs up the assertion that anybody besides the Syrian government has the ability to use chemical weapons, [or] has used chemical weapons,” White House spokesman Jay Carney said on Tuesday.

Britain’s parliament backed a motion on Thursday requiring Prime Minister David Cameron to give it a veto over any future move to arm Syrian rebels, in a symbolic vote the government said it would heed.

Britain says it has not yet taken any decision to arm rebels fighting to topple President Bashar al-Assad, but its role in helping to lift a European Union arms embargo on Syria in May fuelled speculation it was planning to do just that. The Commons voted by 114-1 to back a motion requiring the government to seek its “explicit prior consent” for any future decision to provide lethal assistance.

A Free Syrian Army fighter gathers homemade weapons in the old city of Aleppo July 6, 2013. REUTERS/Muzaffar Salman

Syria’s ruling Baath party, headed by the country’s embattled President Bashar al-Assad, has announced that its top leadership would be replaced, including Vice President Farouk al-Sharaa.

The party’s central committee “held a lengthy meeting … on Monday morning,” at which “a new national leadership was chosen”, the Baath party website said.

It published the names of 16 members of the new leadership, which included none of the party’s old chiefs with the exception of Assad.

The website said Assad would remain the party’s secretary general. 

Sharaa, who has been Syria’s vice president since 2006, will remain in office despite his removal from the party leadership.

Among those newly elected to the party leadership are parliament chief Jihad al-Laham and Prime Minister Wael al-Halqi.

Bassam Abu Abdullah, director of the Damascus Centre for Strategic Studies, said the overhaul was the result of deep-seated discontent within the Baath party.

“There has been a lot of criticism from within the base towards the leadership, which has been accused of being inflexible, both before and since the crisis,” he said, referring to the Syrian uprising.

“A complete change indicates the failure of leadership and the dissatisfaction from within the Baath party base,” he told AFP.

A second Syrian analyst, speaking on condition of anonymity, said the reshuffle was as a result of “the old leadership’s inability to take the initiative and confront the crisis”.

He noted that the newly appointed leaders include a former ambassador, ex-Syrian envoy to Egypt Yussef Ahmad, for the first time.

“They’ve decided to bring in a younger leadership that is seen as more open to the international community,” he told AFP. The overhaul means that for the first time none of the members of the party’s leadership is a member of the Syrian intelligence forces.

The Baath party has been in power since March 8, 1963 and is the most powerful political party in Syria.

Monday’s meeting of the party’s central committee was the first since 2005, when much of the previous old guard was replaced.

Meanwhile, Syria’s interim rebel prime minister Ghassan Hitto has announced his resignation.

Hitto quit nearly four months after his appointment and after failing to form a government.

His decision comes two days after secular dissident Ahmad Assi Jarba was chosen to lead the opposition. Jarba is seen as close to Saudi Arabia, which opposed the choice of Hitto  to head the interim government in March.

Syrian troops fought with rebels in Homs on Monday in a battle seen as crucial to the government’s attempts to drive a wedge between opposition-held areas and establish links between the capital and President Bashar al-Assad’s coastal strongholds.

Assad’s forces have been on the offensive in the central Syrian city for ten days, hitting rebel-held neighborhoods with air strikes, mortar bombs and tanks.

Rebels control much of northern Syria but have been on the back foot against Assad’s army further south since it retook Qusair last month, a town near the border with Lebanon, where victory marked a change in the government’s fortunes.

Homs, 140 km (90 miles) north of Damascus, lies at a strategic crossing linking the capital with army bases in coastal regions controlled by Assad’s Alawite sect, an offshoot of Shi’ite Islam that has dominated majority Sunni Syria since the 1960s.

Assad is trying to cement control of this belt of territory, in a move that could drive a wedge between rebel-held areas in the north and south of the country.

At a time when the army has made gains on the battlefield, Syrian state media announced that new leaders had been appointed in the ruling Baath Party in a reshuffle that will be seen as an attempt by Assad to put a new face on the political organization that has dominated Syrian politics for more than four decades.