The blasts targeting two security service bases in Homs, Syria's third city, killed a top intelligence chief and close confidant of President Bashar al-Assad, and were claimed by former Al-Qaeda affiliate Fateh al-Sham Front.
The Syrian Observatory for Human Rights said in all, 42 people were killed, but the provincial governor put the figure at 30 dead.
Bashar al-Jaafari, the regime's envoy to the talks in Geneva, said Syria would retaliate following the deadly assault.
United Nations envoy Staffan de Mistura said today's suicide attacks were designed to "spoil" the peace talks.
The Homs attacks came a day after 77 people, mostly civilians, were killed in a suicide bombing claimed by the Islamic State group in Al-Bab, said the Observatory. The jihadists were ousted from the northern town this week by Turkish-backed rebels.
In Geneva, Syrian government and opposition negotiators were to continue meetings with de Mistura through the weekend despite little hope for a breakthrough.
The main opposition High Negotiations Committee (HNC) described its meeting with de Mistura as "positive", without elaborating on a possible path forward.
During three previous rounds of talks in Geneva last year, the rivals never sat down at the same table, instead leaving de Mistura to shuttle between them.
The HNC has said it wants to meet the government face-to-face this time.
At the end of yesterday's negotiations, de Mistura's acting chief of staff Michael Contet signalled there was no immediate prospect of direct talks.
"There were at least six attackers and several of them blew themselves up near the headquarters of state security and military intelligence," Observatory director Rami Abdel Rahman said.
Fateh al-Sham Front said just five militants took part in the assault, the latest atrocity in a six-year war which has killed more than 310,000 people.
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