Dozens of Syrian rebel groups have called for unity in response to Russian air strikes and vowed to attack Russian forces in Syria.
Forty-one groups, including the powerful Ahrar al-Sham faction and some units fighting under the Free Syrian Army, condemned "the Russian-Iranian alliance occupying Syria" in a statement released on Monday.
The rebels called on regional states to form an alliance against Russian and Iranian forces fighting on behalf of President Bashar al-Assad's regime.
Russia began to strike Syria last Wednesday, saying it targeted the Islamic State of Iraq and the Levant (ISIL) group.
But the Syrian opposition is concerned the Russian objective is not just to target ISIL but to weaken opponents of the Assad government.
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The 41 groups which signed the statement did not include al-Qaeda's Syria wing, the Nusra Front, which has joined Ahrar al-Sham in a fighting force that has captured most of Idlib province in the northwest.
The opposition says Nusra's allegiance to al-Qaeda is being used by the Syrian and Russian governments to justify their attacks.
Mahmoud al-Louz, a media activist in Homs province, where Russia has launched strikes since the first day of its operation, said Nusra has good relations with other brigades and the people because it is fighting the regime.
"They are using Nusra's presence as an excuse to kill civilians and fight the opposition," he told Al Jazeera.
While Russian strikes have targeted some ISIL positions, the majority have hit anti-government rebels advancing towards the state-controlled Latakia province.
Source: Al Jazeera