Damascus, September 19 (RHC)-- A senior adviser to Syria's President Bashar al-Assad has accused U.S.-led coalition forces of carrying out "intentional" airstrikes against a Syrian military airbase in Dayr al-Zawr province, where 90 soldiers were killed. 

Buthaina Shaaban said in an interview with AFP on Sunday: "None of the facts on the ground show that what happened was a mistake or a coincidence."  The Syrian official also blamed Washington and its allies for colluding with the Takfiri Daesh terrorist group in the region. 

"Everything was calculated and Daesh knew about it... Even Russia reached the terrifying conclusion that the United States is colluding with Daesh," Shaaban stated, adding: "When Daesh advanced, the raids stopped." 

The coalition aircraft, purportedly fighting Daesh in Syria, bombed the airbase on Saturday. In addition to the 90 killed, at least one hundred soldiers were also injured.  Two F-16 and two A-10 jets entered the Syrian airspace from Iraq to conduct the attacks.  The U.S. military says it halted the raids after Russian officials said the targets were Syrian government forces and not Daesh terrorists.  

Elsewhere in her remarks, Shaaban said since the U.S.-led intervention began in Syria in 2014, "We have been saying that this is not against Daesh, that they are not striking Daesh."  The so-called coalition has been conducting the airstrikes in Syria without any authorization from Damascus or a UN mandate. 

Washington and some of its regional allies have supported Takfiri groups fighting against Syria's government. 

Buthaina Shaaban, the senior adviser to Syrian President Bashar al-Assad, said such attacks could endanger a U.S.-Russia brokered ceasefire deal meant to end hostilities in the conflict-ridden Arab country.   She added that Damascus believed the Saturday raids may signal divisions within the U.S. administration on deepening cooperation between Washington and Moscow under the truce deal.