Assad regime's chief negotiator at UN-sponsored talks in Geneva demanded Saturday that all opposition parties at the talks condemn the deadly assault in Homs or be considered "accomplices of terrorism".

"Any party who refuses to condemn these attacks today we will consider that party to be an accomplice of terrorism," Bashar al-Jaafari said after his latest meeting with UN mediator Staffan de Mistura, who he said should also condemn the attacks.

"What happened today has cast a shadow over Geneva", he added, saying it was "not only a military terrorist attack it was also a political attack".

"What happened today will not go unnoticed and we will react to it ... The blood of Syrians is precious and those who kill Syrians will also be punished," he added.

The suicide assaults on two security service bases in Syria's third city of Homs killed dozens of people, including a top intelligence chief, overshadowing the Geneva talks.

Meanwhile, Syria's main opposition's High Negotiations Committee (HNC) spokesman Salem al-Muslat said at the fresh round of peace talks that they "will never be the reason for the negotiations to fail."

Muslat stated that they came to the Geneva talks under the "same hard conditions" where the regime's attacks on the opposition-held areas continued despite the cease-fire agreements.

"Until now, we have not seen any seriousness by the regime. The regime only believes in military solution, killing and destruction," he said.

Syria's former Al-Qaeda affiliate Fateh al-Sham Front claimed the spectacular assault which targeted and killed General Hassan Daabul, a close confidant of Bashar al-Assad.

The Syrian Observatory for Human Rights said 42 people were killed when the bombers targeted the headquarters of state security and military intelligence in the heavily guarded Ghouta and Mahatta neighborhoods.

Provincial governor Talal Barazi said 30 people were killed and 24 wounded.