The U.N. Security Council began a second day of talks on Syria Tuesday after President Bashar al-Assad's tanks shelled the protest hub of Hama on the opening day of the Muslim holy month of Ramadan.

At least 24 civilians were reported killed across the country on Monday, among them 10 during protests after special evening prayers, Syrian Observatory for Human Rights chief Rami Abdul Rahman said.

The European Union ambassador to Syria is to remain in Damascus despite an Italian proposal Tuesday to recall all ambassadors from the 27 EU nations.

"Our ambassador will remain in Damascus to observe what's happening on the ground," said Michael Mann, spokesman for EU foreign policy chief Catherine Ashton.

The United States on Monday weighed possible further sanctions against Damascus as it hoped for "a strong and unified message" from the U.N. Security Council over the deadly crackdown in Syria.

"We've issued now several sets of sanctions against (President Bashar) Assad and his regime," State Department deputy spokesman Mark Toner told reporters.

The Syrian army pressed on Monday with a deadly crackdown on anti-regime dissent, even as international condemnation swelled ahead of a U.N. meeting on the crisis.

The Local Coordination Committees reported Monday evening that the army was firing tank shells and machinegun rounds at several neighborhoods in the flashpoint protest city of Hama. One person was killed in the shelling, the committees said.

European Union foreign policy chief Catherine Ashton on Monday called for a "clear" U.N. stance to end violence in Syria as the 27-nation bloc tightened the screws on Damascus by beefing up sanctions.

"It is time for the Security Council to take a clear stand on the need to end the violence," Ashton said as President Bashar al-Assad faced mounting global condemnation of his regime's unrelenting violence against protesters.

Germany Monday condemned what it called a war by the Syrian government against its own people, after calling for a meeting of the United Nations Security Council on the latest deadly crackdown.

Foreign ministry spokesman Martin Schaefer renewed Berlin's call for a robust response from the council and new European Union sanctions against Damascus after activists said security forces killed nearly 140 people Sunday.

EU foreign policy chief Catherine Ashton on Sunday condemned the "totally unjustified assault" by Syria's military on anti-regime protesters, which activists said had claimed nearly 140 lives Sunday.

"I am shocked at the latest reports from Syria that large numbers of civilians have again been killed in a totally unjustified assault by Syrian security forces on the town of Hama," Ashton said in a statement.

Italy called for urgent U.N. Security Council talks on Syria and said European ambassadors in Damascus should meet on Monday following a deadly crackdown by the Syrian army on anti-regime protesters.

"We request that the United Nations Security Council hold an urgent meeting and adopt a very firm position," Foreign Minister Franco Frattini said in an interview with the public broadcaster RAI.

Turkey urged the Syrian government Sunday to halt deadly attacks on civilians and use peaceful methods to end the unrest.

"Turkey one more time repeats its call for the Syrian government to stop the (military) operations and choose political methods, dialogue and peaceful initiatives for a solution," the foreign ministry said in a statement carried by Anatolia news agency.

U.S. President Barack Obama said he was "appalled" by Syria's crackdown on Sunday which activists say killed nearly 140 people and vowed to step up pressure on President Bashar al-Assad's regime.

In a statement, Obama saluted demonstrators who have taken to the streets as "courageous" and said Syria "will be a better place when a democratic transition goes forward."