The Arab League has approved sanctions against Syria, including an asset freeze and an embargo on investments.
Meeting in Cairo, Egypt, on November 27, league foreign ministers adopted the unprecedented sanctions by a vote of 19 to three.
The move came after Syria refused to allow 500 Arab League monitors into the country to assess the situation on the ground.
The UN estimates about 3,500 people have died as Syria has sought to put down anti-government protests over the past months.
Syria, one of the founder members of the Arab League, condemned the sanctions as a betrayal of Arab solidarity.
Syrian Foreign Minister Walid al-Muallem accused the league of seeking to "internationalise" the conflict.
Qatari Prime Minister and Foreign Minister Sheikh Hamad bin Jassim al-Thani gave details of the sanctions to a news conference in Cairo. They include: Cutting off transactions with the Syrian central bank Halting funding by Arab governments for projects in Syria A ban on senior Syrian officials travelling to other Arab countries A freeze on assets related to President Bashar al-Assad's government
The league also voted to impose a ban on commercial flights between Syria and member states. A date for the ban to enter into force will be agreed within the next week.
The declaration also calls on Arab central banks to monitor transfers to Syria, with the exception of remittances from Syrians abroad.