United Nations (CNN) -- The U.N. Security Council met Monday to discuss Syria amid reports of continuing clashes between the military and civilians.
The four European members of the Security Council -- Britain, France, Germany and Portugal -- have revived a draft U.N. resolution that would likely condemn the government of President Bashar al-Assad, diplomats said after the meeting.
Ambassadors from other nations, including China and Russia, have previously argued that U.N. action would risk further destabilizing the Middle Eastern nation. It was not immediately clear whether they would support such a resolution.
Still, India's ambassador to the United Nations, Hardeep Singh Puri, who is also this month's council president, said afterward that he had "detected a certain convergence of thinking, concern about the escalating violence."
The Security Council is expected to meet again Tuesday morning.
Meanwhile, in Washington, Secretary of State Hillary Clinton reiterated her assertion that al-Assad has lost his legitimacy with the Syrian people.
"We call on those members of the United Nations Security Council who have opposed any Security Council action that would call on Assad to stop the killing to reconsider their positions," she said in a statement. "And we call on the international community to come together behind the people of Syria in this critical time."
Clinton is to meet Tuesday with a group of U.S.-based Syrian activists and representatives of the Syrian-American community "to discuss the urgent situation in Syria," acting spokesman Mark Toner said.
Before the meeting, Amnesty International issued a statement calling on the Security Council to "urgently respond to the ongoing crackdown in Syria by referring the situation to the International Criminal Court."
It said at least 52 people -- including four children -- were killed Sunday in Hama, Syria.
"It's clear that President Bashar al-Assad is unwilling to halt his security forces, so the U.N. must take decisive action to stem this violent campaign of repression," said Philip Luther, Amnesty International's deputy director for the Middle East and North Africa.
He called for, "at the very least," an arms embargo to be imposed, assets of top government officials to be frozen and referral of the matter to the International Criminal Court.
Amnesty said it has received the names of more than 1,500 people believed to have been killed since protests began in mid-March.
"Many of them are reported to be protesters and local residents shot by live ammunition from the security forces and the army," it said. "Based on its research, Amnesty International has concluded that crimes committed amount to crimes against humanity as they appear to be part of a widespread, as well as systematic, attack against the civilian population."
France's minister of foreign and European affairs, Alain Juppe, warned Syria's leaders "that they will be held accountable for their actions."
In a statement, he called on the Security Council to "shoulder its responsibilities by speaking loud and clear."
As the diplomats were meeting, the violence in Syria was continuing unabated. In addition to the scores of deaths reported Sunday, at least six people were killed in Syria on Monday, a human rights organization said.
According to the Syrian Observatory for Human Rights, four people were killed Monday in Hama, in central-western Syria, and two in the central-eastern city of Bou Kamal.
Military tanks at a traffic roundabout on the periphery of Hama opened fire and shelled al-Rayyis Hospital about 200 meters (219 yards) away, a Hama resident said. He said a doctor was shot in the leg.
Shortly after 9 p.m., 50-caliber machine guns mounted on tanks could be heard firing in the eastern section of Hama, an activist there said. He said people in other parts of the city told him they, too, could hear firing coming from areas near them. The timing coincided with the hour when many Muslims would have been heading toward their mosque, he said. Activists had been planning to demonstrate against the government after prayers Monday night.
The Local Coordination Committees of Syria put Monday's death toll by the Syrian military in Hama at three. The Local Coordination Committees are an affiliation of groups that report on protests in the nation.
Human rights groups described Sunday's violence as repression by al-Assad's regime, but the state-run Syrian Arab News Agency said security forces were responding to "armed groups" in Hama and other cities.
Sunday's clashes across the country left at least 71 people dead, with at least 50 killed in Hama, according to the Local Coordination Committees.
Other human rights organizations offered higher tolls. A doctor in Hama said 115 people were killed in and around the city. "It's too much for one day," he said.
CNN was unable to independently confirm the death tolls. Syria has restricted access to Syria by international journalists.
The hospitals in Hama have been overwhelmed; patients were being treated in hallways and the morgues were overflowing, the doctor said.
He said Syrian security forces had targeted those trying to help the wounded.
Al-Assad said Monday that the government was responding to a "vicious attack."
"This vicious attack won't fare any better than the previous ones. ... All of Syria's honest people are confident that we will emerge from the crisis more powerful, more present and more effective regionally and internationally," he said in a speech to the military, state-run SANA news agency reported Monday.
Three members of security forces were killed Sunday in clashes in Hama, and three members of the military were killed in the eastern city of Deir Ezzour, SANA reported.
The news agency said "armed terrorist groups" had taken to the streets in Deir Ezzour, attacking police headquarters and stealing weapons.
The Local Coordination Committees reported that at least 11 people were killed Sunday in the city, and at least one person was killed there Monday.
In Homs, more than 10,000 demonstrators took to the streets Monday, calling for al-Assad to step down and declaring their support for the people of Hama and Deir Ezzour, the Syrian Observatory for Human Rights reported.
Anti-government protesters have taken to the streets in Syria since mid-March to demand a new regime. Activists blame the deaths of demonstrators on security forces, but the government has consistently attributed the violence to "armed groups."
Al-Assad has drawn criticism at home and abroad for his crackdown on protesters calling for his ouster.
The European Union announced Monday an assets freeze and travel ban on five Syrians "involved in or associated with the violent repression," but the EU did not identify them.
Also Monday, Turkey expressed growing dissatisfaction with its neighbor. Violence in Syria has prompted thousands to flee to Turkey.
"We were greatly frustrated and disappointed about the operation in Syria yesterday, especially in Hama," Turkish Foreign Minister Ahmet Davutoglu said. "The timing and the way these operations are conducted are all wrong. We strongly condemn these operations."
The weekend's carnage "shows that the Syrian leadership is unwilling to implement the reforms it has promised in response to the legitimate requests of the Syrian people," the European Union's foreign policy chief, Catherine Ashton, said in a statement.
A spokesman for U.N. Secretary-General Ban Ki-moon said Sunday that the United Nations chief was "deeply concerned" about the reports of casualties.
"He strongly condemns the use of force against the civilian population and calls on the government of Syria to halt this violent offensive at once," the spokesman said in a statement.
CNN's Nada Husseini, Richard Roth, Arwa Damon, Yesim Comert, Rima Maktabi and Salma Abdelaziz contributed to this report.