In an interview with Syrian national television on Thursday, al-Assad said that "the Syrian government is not part of these negotiations nor of these discussions." There are merely delegates in Geneva who have the support of the government and who share its views, he said.
The president played down the legitimacy of the opposition delegates, charging that they represent Turkey and the United States. "A few represent the terrorists," he added.
Ankara and Washington have been supporting forces that are fighting al-Assad's army in the civil war. In contrast, Russia is giving military support to the Syrian president.
UN Secretary General Antonio Guterres on Thursday expressed his hope that these talks could lead towards a broader peace process to end the war that has been going on for more than eight years.
"I hope this will be the first step towards a political solution that will end this tragic chapter in the lives of the Syrian people," he said at a conference in Istanbul, echoing similar remarks by UN Syria envoy Geir Pedersen.
"This is not true," al-Assad said. While the Geneva talks could maybe be part of the solution, the war could not end until terrorism has been defeated in Syria, he said.
The government has been using the terrorism label both for the armed opposition and for extremist groups.
Earlier on Thursday, a heated debate over the Syrian army's role in the civil war overshadowed the first working session of the talks between the warring sides in Geneva, according to participants.
Syrian opposition sources said that a dispute erupted when a member of the government lauded the army and its "martyrs." 
Opposition delegates protested, and a high-volume debate ensued.
Several previous rounds of UN-mediated Syria talks did not yield an outcome, as the government and opposition failed to engage in substantive negotiations.
Expectations for the new Geneva talks have been dampened by the army's territorial gains in past months, which could decrease the government's willingness to make concessions.
A Syrian opposition delegate told dpa that the talks can only be successful if the government feels pressure from its ally Russia.
"I don't think that the regime will be involved positively," Jamal Suleiman said.
"Without Russian pressure, the regime would not have come to Geneva," added Suleiman, a well-known Syrian actor who lives in Cairo.
He argued that the government's position is not as strong as it seems, as its military victories depend on Russian military support.
"They don't own that. Russians own that. They know that very well," Suleiman said.
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