Syrians gather where three bombs exploded in Sayeda Zeinab, a predominantly Shiite Muslim suburb of Damascus on Sunday. The triple bombing claimed by the extremist Islamic State group killed at least 45 people. (SANA via AP)

A triple suicide bombing in Damascus clouded the already shaky peace process that was still struggling Sunday to get off the ground here.

The Islamic State claimed responsibility for the bombing, which took place near the Shiite Sayeda Zeinab shrine on the southern outskirts of the Syrian capital, killing least 45 people and wounding over 100.

The peace talks officially began Friday, but the Syrian opposition has not agreed to formally participate. Most members of the High Negotiations Committee, formed to participate in the talks, have, however, arrived in Geneva to discuss their concerns about the process with U.N. officials.

The Syrian government, speaking publicly for the first time since the talks began, suggested Sunday that even if the opposition does agree to join in the process, the government may not accept all members of its team as negotiating partners.

Bashar al-Jaafari, the Syrian envoy to the United Nations and head of the government negotiating team in Geneva, said the team will refuse to hold negotiations with any members of the opposition whom the government defines as “terrorists.”

In a brief statement Sunday, Jan. 31, Secretary of State John Kerry called for the continuation of Syrian peace talks in Geneva and for immediate steps to increase food aid and other humanitarian assistance to Syrians. (U.S. Department of State)

“We don’t know yet who will be sitting with us,” he said. “We don’t deal with terrorists.”

The government is pressing for the inclusion of a separate group of individuals who are considered opponents by the government and have called for reforms, but not the ouster of Syrian President Bashar al-Assad.

The main Syrian opposition team continued to stand by its insistence that steps should be taken to implement clauses in U.N. Security Council resolutions dealing with the delivery of humanitarian aid to towns besieged by government forces, the release of political prisoners and a halt to the aerial bombardments of civilian areas. Opposition members met Sunday with the U.N. special envoy for Syria, Staffan de Mistura, to air their demands.

Secretary of State John F. Kerry sought on Sunday to reassure the opposition that its concerns about the dire humanitarian conditions in Syria are taken seriously by the United States.

“The Syrian regime has a fundamental responsibility — all the parties to the conflict have a duty — to facilitate humanitarian access to populations in desperate need, not in a week, not after further discussions, but right now, today,” he said. Under U.N. Security Council resolution 2254, which mandated the peace process, “the government and all parties have an obligation, as well, to cease bombings and other attacks against civilians.”

Jaafari said the government was prepared to discuss the delivery of humanitarian aid, but not as a precondition for starting the talks. The Syrian government’s priority is to push for the implementation of a different Security Council resolution, 2253, which calls on the international community to battle terrorism.

Carol Morello in Washington contributed to this report.