BEIRUT (AP) _ In an unprecedented move against an Arab nation, the Arab League on Sunday approved economic sanctions on Syria to pressure Damascus to end its deadly suppression of an 8-month-old uprising against President Bashar Assad.

But even as world leaders abandon Assad, the regime has refused to ease a military assault on dissent that already has killed more than 3,500 people. On Sunday, Damascus slammed the sanctions as a betrayal of Arab solidarity and insisted a foreign conspiracy was behind the revolt, all but assuring more bloodshed will follow.

The sanctions are among the clearest signs yet of the isolation Syria is suffering because of the crackdown. Damascus has long boasted of being a powerhouse of Arab nationalism, but Assad has been abandoned by some of his closest allies and now his Arab neighbors. The growing movement against his regime could transform some of the most enduring alliances in the Middle East and beyond.

At a news conference in Cairo, Qatari Foreign Minister Hamad bin Jassim said 19 of the League's 22 member nations approved a series of tough punishments that include cutting off transactions with the Syrian central bank, halting Arab government funding for projects in Syria and freezing government assets. Those sanctions are to take effect immediately.

Other steps, including halting flights and imposing travel bans on some, as-yet unnamed Syrian officials, will come later after a committee reviews them.

``The Syrian people are being killed but we don't want this. Every Syrian official should not accept killing even one person,'' bin Jassim said. ``Power is worth nothing while you stand as an enemy to your people.''

He added that the League aims to ``to avoid any suffering for the Syrian people.''

Iraq and Lebanon _ important trading partners for Syria _ abstained from the vote, which came after Damascus missed an Arab League deadline to agree to allow hundreds of observers into the country as part of a peace deal Syria agreed to early this month to end the crisis.

Arab League Secretary General Nabil Elaraby said the bloc will reconsider the sanctions if Syria carries out the Arab-brokered plan, which includes pulling tanks from the streets and ending violence against civilians.

The regime, however, has shown no signs of easing its crackdown, and activist groups said more than 30 people were killed Sunday. The death toll was impossible to confirm. Syria has banned most foreign journalists and prevented independent reporting inside the country.

The Local Coordinating Committees, a coalition of Syrian activist groups, praised the sanctions but called for a mechanism to ensure compliance.

``The sanctions leave open the opportunity for the regime to commit fraud and strip the sanctions of any substance, thereby prolonging the suffering of the Syrian people at the hands of an oppressive and brutal regime,'' the group said.

The Arab League move is the latest in a growing wave of international pressure pushing Damascus to end its crackdown. The European Union and the United States already have imposed sanctions, the League has suspended Syria's membership and world leaders increasingly are calling on Assad to go. But as the crisis drags on, the violence appears to be spiraling out of control as attacks by army defectors increase and some protesters take up arms to protect themselves.

Syria has seen the bloodiest crackdown against the Arab Spring's eruption of protests, and has descended into a deadly grind. Though internationally isolated, Assad appears to have a firm grip on power with the loyalty of most of the armed forces, which in the past months have moved from city to city to put down uprisings. In each place, however, protests have resumed.

The escalating bloodshed has raised fears of civil war _ a worst-case scenario in a country that is a geographical and political keystone in the heart of the Middle East.

Syria borders five countries with whom it shares religious and ethnic minorities and, in Israel's case, a fragile truce. Its web of allegiances extends to Lebanon's powerful Hezbollah movement and Iran's Shiite theocracy. Chaos in Syria could send unsettling ripples across the region.

For now, Assad still has a strong bulwark to prevent his meeting the same fate as the leaders of Egypt, Tunisia or Libya anytime soon. His key advantages are the support of Russia and China, fear among many Syrians about a future without Assad, and the near-certainty that foreign militaries will stay away.

But the unrest is eviscerating the economy, threatening the business community and prosperous merchant classes that are key to propping up the regime. An influential bloc, the business leaders have long traded political freedoms for economic privileges.

The opposition has tried to rally these largely silent, but hugely important, sectors of society. But Assad's opponents have failed so far to galvanize support in Damascus and Aleppo _ the two economic centers in Syria.

Sunday's sanctions, however, could chip away at their resolve.

Since the revolt began, the regime has blamed the bloodshed on terrorists acting out a foreign conspiracy to divide and undermine Syria. The bloodshed has laid bare Syria's long-simmering sectarian tensions, with disturbing reports of Iraq-style sectarian killings.

Syria is an overwhelmingly Sunni country of 22 million, but Assad and the ruling elite belong to the minority Alawite sect. Assad, and his father before him, stacked key military posts with Alawites to meld the fates of the army and the regime _ a tactic aimed at compelling the army to fight to the death to protect the Assad family dynasty.

Until recently, most of the bloodshed was caused by security forces firing on mainly peaceful protests. Lately, there have been growing reports of army defectors and armed civilians fighting Assad's forces _ a development that some say plays into the regime's hands by giving government troops a pretext to crack down with overwhelming force.