Dozens of soldiers and security forces were gunned down by suspected army defectors in southern Syria, a deadly ambush that comes as President Bashar Assad increasingly appears unable to manage the crisis, activists said Tuesday.

Monday's hours-long clash in the southern province of Daraa came on a particularly bloody day in Syria, with as many as 90 people killed across the country. The brazen attack by the army defectors suggested a new confidence among troops who have sided with the protesters and highlighted the potential for an armed confrontation to escalate.

The U.N. estimates the regime's military crackdown on an 8-month-old uprising has killed 3,500 people in the past eight months. November is shaping up to be the bloodiest month of the revolt, with well over 300 people killed so far.

The latest death toll was compiled by sources including British-based Syrian Observatory for Human Rights, the Local Coordination Committees activist coalition and morgue officials.

Rami Abdul-Rahman, head of the observatory, confirmed that 34 soldiers were killed in an ambush in Daraa, the birthplace of the uprising that began in mid-March, inspired by successful revolts in Tunisia, Egypt and later Libya.

Although activists say the protests have remained largely peaceful, with demonstrators calling for the regime's downfall, an armed insurgency has developed in recent months targeting Assad's military and security forces.

Assad is facing the most severe challenge to his family's four-decade rule in Syria, with former allies as well as Western nations using increasingly harsh rhetoric in urging him to stop his bloody crackdown. On Tuesday, Turkey said it no longer has confidence in the Syrian regime and warned Assad that his brutal crackdown threatens to place him on a list of leaders who "feed on blood."

Prime Minister Tayyip Erdogan's comments were a blow to Syria, because the countries once cultivated close ties. But Turkish leaders have grown increasingly frustrated with Damascus over its refusal to halt the attacks on protesters.

Adding to the blow, Turkey also on Tuesday canceled plans for joint oil exploration in Syria and threatened to cut electricity supplies after a spate of attacks on Ankara's embassy in Damascus and consulates the cities of Aleppo and Latakia.

On Monday, Jordan's King Abdullah II said Assad should step down for the good of his country, the first Arab leader to publicly make such a call.

That prompted pro-government protesters to converge on Jordan's embassy in Damascus, with three of them scaling the fence and ripping down the Jordanian flag _ the latest in a string of attacks on foreign missions. Jordan's Foreign Ministry spokesman Mohammad Kayed said no one entered the embassy and no injuries occurred.

Monday's bloodiest attacks were in Daraa province, along the Jordanian border, including the attack that killed 34 soldiers. According to the observatory, 12 defectors and 23 civilians also killed in the area.

A resident near the town of Khirbet Ghazaleh in Daraa province said he heard more than four hours of intense gunfire. He asked that his name not be used for fear of government reprisals.

Another witness, who is an activist in the area, said he counted the bodies of 12 people, believed to be civilians killed by security forces' fire.

"I saw two army armored personnel carriers, totally burnt," he told The Associated Press by telephone. He also asked for anonymity out of fear for his safety.

In the restive city of Homs, the morgue received 19 corpses, all of them shot.

Other activist groups had slightly different figures of those killed, a common occurrence because the Syrian government has prevented independent reporting and barred most foreign journalists. Details gathered by activist groups and witnesses are key channels of information.

Syria's crackdown has brought international condemnation, but Damascus generally had been spared broad reproach in the Arab world. That changed Saturday, with a near-unanimous vote by the 22-member Arab League to suspend Syria, and the situation appeared to be spiraling out of Assad's control.

Earlier Monday, Syria struck back at its international critics, branding an Arab League decision to suspend its membership as "shameful and malicious" and accusing other Arabs of conspiring with the West to undermine the regime.

The sharp rebuke suggests Damascus fears the United States and its allies might use the rare Arab consensus to press for tougher sanctions at the United Nations.

Assad says extremists pushing a foreign agenda to destabilize Syria are behind the unrest, not true reform-seekers aiming to open the country's autocratic political system.

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Associated Press writer Selcan Hacaoglu in Ankara, Turkey, contributed to this report.