Syrian president Bashar Assad's brother-in-law is among the dead after a bombing in Damascus, state-run TV said.
General Assef Shawkat - who was married to Assad's elder sister, Bushra - was the deputy defence minister and was among the most feared figures in Assad's inner circle.
Defence minister Dawoud Rajha and former defence official Hassan Turkmani were also killed in the blast at the National Security building in the Syrian capital during a meeting of cabinet ministers and senior security officials. Interior minister Mohammed Shaar was wounded and is in a stable condition.
Syria's rebel commander Riad al-Asaad said his forces planted a bomb inside the room where senior government officials were meeting. He added that all those who carried out the operation are safe, and added: "God willing, this is the beginning of the end of the regime. Hopefully Bashar will be next."
Damascus has seen four straight days of clashes pitting government troops against rebels, who are trying to bring down the regime by force, and the suicide bombing came as government troops reportedly inflicted heavy casualties on rebel forces in the city.
The SANA news agency said troops were chasing rebels in the Midan neighbourhood, causing "great losses among them", and the Britain-based Syrian Observatory for Human Rights said army helicopters attacked the neighbourhoods of Qaboun and Barzeh.
Meanwhile, the UN Security Council delayed a vote on a new Syria resolution until Thursday in a last-minute effort to get key Western nations and Russia to reach agreement on measures to end the escalating violence.
International envoy Kofi Annan urged the council to delay the scheduled vote and ambassadors from the five veto-wielding permanent council nations - the US, Russia, China, the UK and France - met behind closed doors to discuss the request.
Russia's UN ambassador Vitaly Churkin later told reporters: "A possible vote has been postponed until tomorrow morning."