Moscow insisted on Tuesday that a new Security Council resolution on Syria not allow the use of force, while the Arab country's main opposition group demanded a swift international response following the UN report that confirmed chemical weapons were used outside Damascus last month.
Meanwhile, a car bomb exploded at a crossing point along the country's volatile border with Turkey, Syrian activist groups said. At least 15 people were wounded in the explosion at the rebel-controlled Bab al-Hawa crossing, they said.
In Moscow, Foreign Minister Sergey Lavrov said Russia "spoke clearly" about rejecting the use of force when the agreement on Syria abandoning its chemical weapons was worked out in Geneva between U.S. and Russian envoys.
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But if signs emerge that Syria is not fulfilling the agreement or there are reports of further chemical weapons use, "then the Security Council will examine the situation," Lavrov said, suggesting the issue could be reconsidered. He spoke at a news conference with French counterpart Laurent Fabius. France and the United States say a military option remains on the table and are pushing for the UN resolution to reflect that.
The meeting came a day after UN inspectors submitted their report on the Aug. 21 chemical weapons attack that precipitated the heightened tensions over Syria. It was the first official confirmation by impartial experts that chemical weapons were used in the attack near Damascus, which killed hundreds.
Although the report confirmed chemical weapons were used, it did not say who used them — and Lavrov and Fabius differed sharply on their interpretations.
"The report exposes the regime," Fabius said. "On the basis of the information of our external agents, we consider that the report proves the responsibility of the regime for the chemical weapons attack of Aug. 21."
The U.S., Britain and France jumped on evidence in the report — especially the type of rockets, the composition of the sarin agent, and trajectory of the missiles — to declare that President Bashar al-Assad's government was responsible. Russia, a staunch ally of the Syrian regime, disagreed.
Lavrov said the Russian side has "serious reason to suggest that this was a provocation" by the rebels fighting Assad's forces.
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In Damascus, the Foreign Ministry slammed the U.S., British and French foreign ministers, accusing them of trying to impose their agenda on the Syrian people. The ministry statement came in response to recent demands by the three ministers that Assad step down even as the West increases efforts to bring the warring sides to an international peace conference.
The statement denounced the three ministers for "their frantic quest to impose their will" on the Syrian people, stressing that any talk about the political and constitutional legitimacy in Syria is an "exclusive right for the Syrian people."
"It's impermissible for the United States, its allies and tools" to impose their will in this regard, the statement said. "Assad is the legitimate president chosen by the Syrian people and will remain so as long as the Syrian people want this."
Syria rebels demand response to UN report
The main Syrian opposition group, the Western-backed Syrian National Coalition, said the UN report offered "damning and irrefutable evidence" and clearly shows that only the Syrian regime could have carried out the attack, which UN chief Ban Ki-moon denounced as a "war crime."
The SNC said there must be a swift response and called on the UN to refer Syria to the International Criminal Court.
"The Syrian coalition urges the Security Council to end the culture of impunity in Syria, and to stop the Syrian regime from carrying out further war crimes and crimes against humanity," the coalition said.
The report, Ban said at the UN on Monday, was "the most significant confirmed use of chemical weapons against civilians since Saddam Hussein used them" in Halabja, Iraq, in 1988, and "the worst use of weapons of mass destruction in the 21st century."
The UN inspectors report said surface-to-surface rockets loaded with the nerve agent sarin had been fired from an area where Syria's military has bases, but said the evidence could have been manipulated in the rebel-controlled neighbourhood that was struck.
The explosion at the Bab al-Hawa border crossing with Turkey on Tuesday was not the first such attack. In February, a car bomb exploded at the border post, killing 14 people and narrowly missing 13 Syrian opposition figures who were crossing into Turkey. And in May, 43 people were killed when two car bombs exploded on Turkish side of the border.
In Idlib, activist Ahmad al-Khatib said the latest bombing wounded 19 people, both civilians and rebels who were manning a checkpoint. Rami Abdul-Rahman who heads the Britain-based Syrian Observatory for Human Rights said 15 people were wounded.
Syria accuses Turkey of escalating tensions
Earlier Tuesday, the Syrian military accused Turkey of seeking to escalate tensions along the border by shooting down a Syrian military helicopter there the day before.
The military said the helicopter was on a mission to monitor for cross-border infiltration of rebels when it "mistakenly" entered Turkish airspace.
Turkey's deputy prime minister Bulent Arinc told reporters in Ankara on Monday that the aircraft was shot down by a fighter jet after it ignored repeated warnings to leave Turkish airspace.
The helicopter had strayed two kilometres over Turkey but crashed inside Syria after being hit by missiles fired from the Turkish jet. Arinc said he did not have any information on the fate of the Syrian pilots.
The observatory said rebel fighters captured one of the two crew members, while the fate of the other was unclear.
The Syrian military said the helicopter entered Turkish space "for a short distance" by mistake. "The hasty reaction from the Turkish side, particularly that the helicopter was heading back and was not on a fighting mission, reveals the real intentions" of Ankara to ramp up tensions, it said.
Turkey has been at odds with the Syrian government since early in the country's civil war and has backed the Syrian rebels, while advocating international intervention in the conflict.
Turkish Foreign Minister Ahmet Davutoglu, speaking in Paris after meetings about Syria with his counterparts from other countries, said Monday's incident should send a message. "Nobody will dare to violate Turkey's borders in any way again," he said, according to Anatolia, the Turkish state-run news agency. "The necessary measures have been taken."
Also Tuesday, Syrian government troops backed by Lebanon's Hezbollah fighters captured parts of the town of Chebaa, the Observatory said. The town lies just south of Damascus near the road leading to the city's international airport. Members of the Lebanese militant group have been fighting alongside Assad's forces in the conflict.
Chebaa is also close to the Sayida Zeinab shrine, a holy place for Shiites. Hezbollah's leader Sheik Hassan Nasrallah has warned in the past that Sunni extremists were planning to blow up the golden-domed shrine.