The European Union expanded its sanctions against Syria on Monday, imposing asset freezes and travel bans against five more military and government officials.
The EU decision brings the number of individuals targeted by the EU to 35, including President Bashar Assad. Four government entities are also on the list.
The EU said it would release the names of the new additions to the list on Tuesday.
In Washington, President Barack Obama said the latest attacks on anti-government demonstrations in Syria, launched as the Muslim holy month of Ramadan began, were "outrageous." U.S. Secretary of State Hillary Rodham urged Assad "to stop the slaughter now."
On Monday, Syrian forces shelled the city of Hama for a second day and fired at worshippers heading to Ramadan prayers. Violence on Sunday left 74 people dead throughout the country, 55 of them from Hama and nearby, according to rights groups.
It was one of the bloodiest days since the uprising against Assad's authoritarian rule in Syria began in mid-March. More than 1,600 civilians have been killed in a crackdown on largely peaceful protests since a popular uprising began in Syria in mid-March.
EU foreign policy chief Catherine Ashton condemned Syria's crackdown on pro-democracy protesters. Attacks by the security forces showed that the leadership is "unwilling to implement the reforms it has promised in response to the legitimate requests of the Syrian people," Ashton said.
The European Union also has an embargo on sales of arms and equipment that can be used to suppress demonstrations.
"I wish to remind the Syrian authorities of their responsibility to protect the population," Ashton said. "The brutal violence creates a serious risk of escalating tension and factional divisions and is not consistent with broad reforms."
"We are keeping the situation under constant review and we will continue with this policy of putting pressure _ economic pressure and political pressure _ on the Syrian regime," spokesman Michael Mann said.
In Paris, French Foreign Ministry spokeswoman Christine Fages said political, military and security officials in Syria "must know, now more than ever, that they will have to be held accountable for their acts."
French government spokeswoman Valerie Pecresse, after a weekly Cabinet meeting Monday, said France was also calling on the U.N. Security Council to "condemn this violence" over the weekend in Syria.
The U.N. Security Council scheduled closed-door consultations on Syria on Monday afternoon, said an official who asked not to be identified because he was not authorized to speak publicly.
Germany asked for the briefing following Sunday's attacks by Syrian troops.
Germany, Britain, France and Portugal have tried unsuccessfully since April to get the U.N.'s most powerful body to condemn Syrian attacks on unarmed civilians. The United States strongly supports their efforts and a draft resolution the Europeans circulated in late May, but they have faced opposition from Russia, China, South Africa, Brazil and India, which holds the council presidency this month.
The resolution's opponents have so far opposed measures condemning Damascus for its crackdown, partly because they fear that it may be used as a pretext for armed intervention against Syria. They say a resolution allowing the use of all means to protect the civilian population in Libya has been misused by NATO to justify five months of airstrikes against Moammar Gadhafi's regime.
They have instead called for stepped up mediation to encourage reforms that President Bashar Assad has promised.
Amnesty International also urged the Security Council to take action over the Syria bloodshed and to refer the culprits to the international war crimes court.
"It's clear that ... Assad is unwilling to halt his security forces, so the UN must take decisive action to stem this violent campaign of repression," said Amnesty International's Deputy Director Philip Luther.
Britain's foreign secretary, William Hague, called for tougher sanctions against Assad's government, but cautioned that military action was "not a remote possibility." He said such sanctions had to come from both Western nations, and Arab countries and regional powers like Turkey.
Turkish Foreign Minister Ahmet Davutoglu condemned the continued crackdown on Syria's protesters, saying nobody can remain silent when "more than 100 people were killed in one day."
The latest attacks in Hama involving tanks in an urban environment on the eve of the Muslim holy month of Ramadan were "a very wrong signal to the Syrian people, to the Muslim world and to the global community," he said during a visit in Oslo, Norway.
Davutoglu said Turkey does not seek an "internationalization" of the conflict but counts on Syria to push forward with the implementation of democratic reforms.
AP Jamey Keaten in Paris, Jill Lawless in London, Edith M. Lederer at the United Nations and Matthew Lee in Washington contributed to this report.