BEIRUT (AP) — The leader of Syria’s main opposition group rejected calls Friday by U.N. envoy Kofi Annan for dialogue with President Bashar Assad’s government, saying such talks are pointless and unrealistic as long as the regime massacres its own people.

As the prospects for diplomacy faltered, a Turkish official said two Syrian generals, a colonel and two sergeants defected to Turkey on Thursday, a day after Syria’s deputy oil minister also deserted Assad’s regime, making him the highest-ranking civilian official to join the opposition.