Syria's Defence Minister Dawoud Rajha has been killed in a suspected suicide bombing at a high-level security meeting in Damascus, state television reports.
Gen Rajha, former army general, was the most senior Christian government official in Syria. President Assad appointed him to the post last year.
State television has also confirmed that Gen Rajha's deputy - and President Assad's brother-in-law - Assef Shawkat has also been killed.
In a newsflash, it announced the "martyrdom of deputy defence minister General Assef Shawkat in the terrorist bombing which targeted the National Security building in Damascus".
The Free Syrian Army and a Syrian rebel islamist group, Liwa Al-Islam, has claimed responsibility for the bombing .
A military statement read out on state television said:
"The armed forces are determined to terminate the killing gangs and criminals and pursue them wherever they go.
"Whoever thinks that by targeting some commanders they can twist Syria's arm, is delusional".
Video report by Paul Davies.
Other officials have also been wounded and taken to hospital including the country's interior minister who is reported to in a "stable condition".
Security sources have said that Syrian intelligence chief Hisham Bekhtyar is wounded and undergoing surgery.
According to security sources, an alleged suicide bomber who detonated explosives at the meeting of ministers and President Bashar al-Assad's top security and military officials was a bodyguard for the president's inner circle.
Syria's rebel leader, Riad al-Asaad, has said that his forces carried out the attack. But he denied it was a suicide bombing.
In a phone interview, he told Associated Press that rebel forces planted a bomb inside a room where the senior government officials were meeting.
He also said the attack marked "the beginning of the end of the regime".
An activist in Damascus told ITV News she was happy at the news of the deaths of the officials.
But she also said: "We are on the edge, we don't know what to expect; we are worried and happy".