United Nations experts are investigating the alleged use of chemical weapons in Syria as the United States and allies prepare for the possibility of a punitive strike against President Bashar Assad's regime, blamed by the Syrian opposition for the attack. The international aid group Doctors Without Borders says at least 355 people were killed in the Aug. 21 attack.

Here's a look at key Syria developments around the world Thursday amid heightened tensions over the potential military action:

Syria:

signalling defiance to mounting Western warnings of a possible punitive strike. UN chemical weapons inspectors toured stricken rebel-held areas near the Syrian capital of Damascus for a third day.

Britain:

for military action against Syria, without authorization from the UN Security Council.

France:

The French military is ready to commit forces to an operation in Syria if President Francois Hollande approves it, . Hollande, who met with the head of the Syrian opposition, stopped short of announcing a military intervention.

United Nations:

UN Secretary-General Ban Ki-moon said in Vienna that UN experts seeking to collect evidence from the apparent chemical attack will report to him as soon as they leave the country Saturday. The team is expected to complete its inspection on Friday and their conclusions will be shared with members of the Security Council.

Israel:

Thousands of Israelis crowded gas-mask distribution facilities to get free masks, fearing Israel could be targeted in retaliation by Syria if it is attacked. A mob forcibly took gas masks from a distribution centre in Jerusalem on Wednesday. Officers were deployed to maintain order Thursday in Haifa, where more than 5,000 people waited for protective kits.

Turkey:

against possible chemical attacks from Syria and stocked food and gas masks along their shared border. Bunkers were designated in seven border areas to protect people in the area from harm.

Iran:

his country will press forward with efforts to ward off military action by the U.S. and its allies against the Tehran-backed Syrian regime.

United States:

Republicans and Democrats pressed . Intelligence officials prepared briefings for Congress on evidence they say links Assad's government to last week's attack.

Russia:

Russia's foreign ministry asked the UN to continue its inspection of places where chemical weapons might have been used in Syria. A foreign minister spokesman said the team should inspect three other locations, including a suburb of Aleppo, where the government in Damascus alleges the rebels have used poisoned gas.

Germany:

A poll by ZDF television found that a majority of Germans oppose Western military intervention in Syria and don't want their country to provide backing for any U.S.-led strike.

Lebanon:

any international military action against Syria would pose a "serious threat" to the security and stability of the region, particularly Lebanon.

Egypt:

Egyptian foreign minister Nabil Fahmy said his country strongly opposes military action against Syria and would not support possible punitive strikes by the U.S. and its allies against the Syrian regime.

Romania:

Romania's foreign ministry told its citizens in Syria to leave the country "as soon as possible." They were told to get out via Lebanon, Jordan and Turkey.