Syrian regime and opposition representatives attending the peace talks in Geneva on Saturday warned of the impact on negotiations after a day of violence in Syria that included extremist suicide bombings and missile strikes by regime air force.

Warplanes also carried out six raids on Douma in the eastern suburbs of Damascus, resulting in six deaths, and earlier, an air raid in Hama killed four people from the same family, the Syrian Observatory for Human Rights said.

Suicide bombers stormed two Syrian security offices in Homs on Saturday, killing dozens with gunfire and explosions including the head of military security, prompting airstrikes against the last rebel-held enclave in the western city.

The United Nations opened the peace talks with a symbolic ceremony on Thursday in Geneva, attended by representatives of the warring sides. But there has been no further direct contact with U.N. mediator Staffan de Mistura, who is still trying to get agreement on how the talks should be arranged.