Syrian security forces have shot dead at least 400 civilians in their campaign to crush month-long pro-democracy protests, the Syrian human rights organization Sawasiah said on Tuesday.
The group, founded by jailed human rights lawyer Mohannad al-Hassani, said the United Nations Security Council must convene to start proceedings against Syrian officials in the International Criminal Court and "reign in the security apparatus".
"This savage behavior, which is aimed at keeping the ruling clique in power at the expense of a rising number of civilian lives, calls for immediate international action beyond condemnations," Sawasiah said in a statement sent to Reuters.
"The murderers in the Syrian regime must be held accountable. The rivers of blood spilt by this oppressive regime for the past four decades are enough," the statement said.
Meanwhile on Tuesday, gunfire reverberated in the southern Syrian city at the heart of the uprising against President Bashar Assad, residents said, in a sign that the regime's brutal crackdown was continuing unabated.
Residents of Daraa said that dead bodies still lay on the pavement, while a different human rights group said authorities had detained dozens across the county, including in several Damascus suburbs and in the northern coastal city of Jabla.
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The Syrian Observatory for Human Rights, said security police arrested prominent rights campaigner Qassem al-Ghazzawi on Tuesday in his home city of Deir al-Zor in Syria's impoverished east after protests intensified in the region last week.
Tuesday's developments came a day after the Syrian army, backed by tanks and snipers, launched a deadly raid on Daraa, where the uprising in Syria started over a month ago. Monday's pre-dawn raid left at least 11 dead in the southern city.
The head of the Syrian Observatory for Human Rights, Rami Abdul-Rahman, couldn't provide a precise figure for those arrested in Tuesday's sweeps. He said the group had little news about Daraa since it was difficult to get through after authorities cut mobile telephone service in the city.
A relentless crackdown since mid-March has killed more than 350 people across Syria, with 120 alone dying over the weekend, rights groups said.
But that has only emboldened protesters who started their revolt - inspired by uprisings in the Arab world - with calls for modest reforms but are now increasingly demanding Assad's downfall.
Syria has banned nearly all foreign media and restricted access to trouble spots since the uprising began, making it almost impossible to verify the dramatic events shaking one of the most authoritarian, anti-Western regimes in the Arab world.
Daraa, a drought-parched region of 300,000 in the south, has seen some of the worst bloodshed over the past five weeks as the uprising gained momentum. Recently, the city has absorbed many rural migrants who can no longer farm after years of drought.
The uprising was touched off by the arrest of teenagers who scrawled anti-government graffiti on a wall.
Syria has a pivotal role in most of the flashpoint issues of the Middle East - from the Arab-Israeli peace process to Iran's widening influence. Instability has thrown into disarray the U.S. push for engagement with Damascus, part of Washington's hopes to peel the country away from Hamas, Hezbollah and Tehran.
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