BEIRUT — The main Syrian opposition coalition will decide later this week on whether to take part in peace talks scheduled to resume Wednesday in Geneva, the head of the group said Monday, while violence in northern Syria killed more than a dozen people, despite a partial cease-fire.

Riad Hijab, head of the Higher Negotiations Committee, acknowledged in a teleconference with journalists that Russian bombardment has decreased following the ‘‘cessation of hostilities,’’ which came into effect Feb. 27.

Yet he added that President Bashar Assad’s government has not released any detainees and said the flow of aid to besieged rebel-held areas was too small. These were among the main preconditions for the opposition to attend the indirect talks. The most recent round collapsed last month as the Syrian government launched a new ground offensive.

Hijab said that while the Russian airstrikes have become less frequent, the Syrian government has continued to attack rebels. ‘‘The Russians and the Iranians have caused a catastrophic humanitarian situation that is killing Syrians,’’ Hijab said.

Russia and Iran have been the primary backers of Assad’s government since the civil war began five years ago.

Associated Press