More than 200 people, mostly civilians, were killed on Wednesday in violence across Syria, including 38 in Damascus where armed rebels are pressing an all-out offensive, a monitoring group said.

At least 214 people -- 124 civilians, 62 soldiers and 28 rebels died in one of the bloodiest days of a 16-month revolt against President Bashar Assad's regime, the Syrian Observatory for Human Rights said on Thursday, revising an earlier toll.

U.S. defense officials have held talks with their Israeli counterparts over whether Israel might strike at Syria's weapons facilities as its regime faces possible collapse, the New York Times reported.

The Times on Wednesday cited officials as saying that the Pentagon is not advocating military action because it feels that such an attack would help Syrian President Bashar Assad rally support against foreign intervention.

U.N. chief Ban Ki-moon and international envoy Kofi Annan called on the U.N. Security Council to take strong action on the Syria conflict ahead of a vote Thursday on a western-backed resolution calling for sanctions.

Russia and China are expected to veto the resolution at the 15-nation council despite mounting global concern over Syria after a Damascus bomb attack in which three close associates of President Bashar Assad were killed.

Bulgaria said Thursday a suicide bomber dressed as a tourist and with fake U.S. ID was behind an attack on Israelis on the Black Sea that killed seven people and left two in a coma.

U.S. President Barack Obama called the attack on a bus at Burgas airport on Wednesday, the deadliest against Israelis abroad since 2004, a "barbaric terrorist attack."

Israel accused Iran on Wednesday of being behind a deadly attack against Israeli tourists at an airport in Bulgaria, which Sofia said killed seven people and wounded more than 30 others.

There was no immediate confirmation of the nationalities of the casualties, but Israel's foreign ministry said the blast had targeted a bus carrying Israeli tourists who had just landed at the port city of Burgas on the Black Sea.

The United States moved to freeze the assets of dozens of Syrian ministers Wednesday, piling pressure on the regime as it reeled from a bomb attack that took out three core security officials.

The White House insisted President Bashar Assad was "losing control" of power, as Washington marshaled its forces to push the regime toward its tipping point.

Arab foreign ministers are to hold an emergency meeting on Sunday on the crisis in Syria, Arab League chief Nabil al-Arabi said, after a Damascus bombing on Wednesday killed top security officials.

The meeting in Doha, following a scheduled session of the organization's Syria crisis task force, will "examine the consequences of the situation in Syria from all angles," Arabi said.

Russia on Wednesday demanded the arrest and strict punishment of those behind what it called an "act of terror" in Damascus that killed three top Syrian security officials in a suicide bombing.

"We expect the organizers of the act of terror in Damascus to be identified and for them to face their deserved punishment," the Russian foreign ministry said in a statement.

The U.N. Security Council postponed a vote Wednesday on a Western-drafted resolution calling for sanctions against Syria following a request from international envoy Kofi Annan, diplomats said.

A threat by Russia, President Bashar Assad's key ally, to veto the resolution has sparked new Security Council tensions on Syria.

World powers said a suicide bombing Wednesday that killed three top Syrian officials showed the urgent need for a political transition.

"The French government, without knowing the circumstances of this attack, has always condemned terrorism. That said, given the level of violence, this makes it even more necessary and urgent to find a political transition," French Foreign Minister Laurent Fabius told the French Senate.