The United Nations' top human rights official says Syria's bloody crackdown on anti-government protesters has degenerated into a civil war.

Human Rights Commissioner Navi Pillay told reporters in Geneva Thursday an increasing number of soldiers are defecting and taking up arms against the government. She also said the “reliable information” from Syria indicates the death toll from the past eight months of unrest is far higher than the confirmed U.N. figure of 4,000.

The U.N. Human Rights Council will hold an urgent meeting Friday to discuss the crisis.

But U.S. State Department spokesman Mark Toner said the violence in Syria should be characterized as a civil war, because, he said, the government is overwhelmingly responsible for the use of force.

Syria has refused to end the crackdown, saying it is a necessary response to attacks by “armed terrorists” on civilians and security personnel.

Meanwhile, a report Thursday by the Russian news agency Interfax says Moscow delivered supersonic cruise missiles to Syria, despite calls from the U.S. and Europe for a weapons embargo against the government.

The European Union said it is tightening sanctions on Syria. EU officials also said they added 11 more entities and 12 more individuals to a blacklist hit by travel bans and asset freezes.

An Arab League committee in Cairo also released a list of 17 Syrians banned from traveling to Arab states. Those banned include the brother of Syrian President Bashar al-Assad, top Cabinet ministers and the country's richest businessman.

Officials say the list and other recommendations will be presented to Arab League members meeting in Doha on Sunday.

Arab League member Kuwait on Thursday urged its nationals to leave Syria due to safety concerns. The move follows mob attacks in Damascus on the embassies of Qatar, Saudi Arabia and the UAE after the Arab League decided to suspend Syria's membership.