UNITED NATIONS - The United Nations on Tuesday said "well over 7,500 people" have been killed in Syria due to the government's 11-month crackdown on pro-democracy protesters, raising its previous estimated death toll by more than 2,000."There are credible reports that the death toll now often exceeds 100 civilians a day, including many women and children," UN Under-Secretary-General for political affairs Lynn Pascoe told the UN Security Council. "The total killed so far is certainly well over 7,500 people."Opposition groups say hundreds of civilians have been killed or wounded in the siege of Baba Amro and other rebellious districts in Homs, where terrified residents are enduring dire conditions, without proper supplies of water, food and medicine.Syrian forces on Tuesday launched the heaviest bombardment in their three-week assault on Baba Amro, activists said.Assad, projecting an aura of normality in a land ravaged by 11 months of conflict over his right to power, decreed that a new constitution was in force on Tuesday after officials said nearly 90 percent of voters had endorsed it in a referendum.Opposition groups and Western leaders seeking Assad's removal denounced Sunday's vote as a charade that diverted attention from the violence in Homs and elsewhere.Meanwhile, US Secretary of State Hilary Clinton said Tuesday that an argument could be made that Syrian leader Bashar Assad is a war criminal."There would be an argument to be made that he would fit into that category," Clinton told a Senate committee hearing, responding to a senator's question as to whether Assad could be called a war criminal. But she added that using such labels "limits options to persuade leaders to step down from power."Syrian forces shelled an opposition stronghold in Hama province, killing 20 people, during the day, and hit rebel-held parts of Homs, activists said, as two wounded foreign journalists trapped in the city were reported to have been smuggled safely to Lebanon.Assad sent units of an elite armored division, which is led by his brother Maher, into Homs overnight, activists said. Tanks with the words "Fourth Division Monsters" painted on them moved close to the besieged Baba Amro district.French journalist Edith Bouvier and British photographer Paul Conroy, both wounded last week in an attack in Baba Amro, were now safe in Lebanon, a diplomat and opposition sources said. It was not clear how they escaped.In Hama province, security forces bombarded the town of Helfaya, a hotbed of protests in the uprising against Assad.Activists said the 20 deaths of Sunni Muslim villagers there were among at least 100 killed in the province in the last two weeks in revenge for rebel Free Syrian Army attacks on security forces commanded by members of Assad's minority Alawite sect.The reports could not be independently confirmed. Syrian authorities tightly restrict media access to the country.