BEIRUT — Syria faced the possibility of sweeping economic sanctions from the Arab League on Friday as pressure mounted on Damascus to end the country's bloodshed, even as the military vowed to "cut every evil hand that targets Syrian blood."

The army's defiant statement signaled the country's violence is worsening as President Bashar Assad tries to quash the most serious threat to his family's 40-year dynasty under ever increasing international pressure.

Assad is facing the most severe isolation his country has seen in decades because of the violence, which appears to be spiraling out of control. The largely peaceful uprising against Assad that began in March has become more violent as defectors from the army turn their guns on security forces and some protesters take up arms to protect themselves.

The escalating bloodshed has raised fears of civil war. The U.N. estimates the military crackdown on the revolt already has killed at least 3,500 people. Activists said at least 11 people were killed by security forces Friday.

According to the military's statement, six elite pilots and four technical officers were killed in an ambush on Thursday in Homs, in an unusually high-level strike.

"Our armed forces (will) continue to carry out our mission to defend the country's security, and we will hit back against anything that threatens us," the statement said.

It is not clear who was behind the attacks. It's impossible to independently verify events on the ground because Syria has banned foreign journalists and prevented local reporters from moving freely.

The British-based Syrian Observatory for Human Rights said security forces carried out raids Friday in the village of Furoqlos, near where the pilots were ambushed, and detained 37 people. It gave no further details.

On Thursday, the Arab League gave Syria 24 hours to agree to an observer mission or face sanctions, a humiliating blow to a nation that was a founding member of the Arab coalition.

But the Friday afternoon deadline passed with no agreement. Instead, Arab League Secretary-General Nabil Elaraby received a letter from Syria seeking more details about the proposed observer mission and its legal status.

The League will meet Saturday to decide on sanctions, according to Arab League Deputy Secretary-General Ahmed Ben Heli. The punishments could include halting flights and imposing a freeze on financial dealings and assets.

One senior diplomat said the League would still accept an agreement from Syria by the end of the day — even though the official deadline has passed. But Damascus gave no clear signs that it would bow to the pressure.

The diplomat spoke on condition of anonymity because he was not allowed to speak publicly.

Syria is the scene of the deadliest crackdown against the Arab Spring's eruption of protests, with the U.N. reporting more than 3,500 people killed in eight months. International pressure has been mounting on Assad to stop the killing.

Also Friday, a U.N. human rights panel expressed alarm at reports it received of security forces in Syria torturing children. The Geneva-based Committee against Torture says it has received "numerous, consistent and substantiated reports" of widespread abuse in the country.

Former ally Turkey — now a leading critic of Assad's regime — said allowing the observers would be a "test of goodwill" for Syria.

"Today is a historic decision day for Syria," Turkish Foreign Minister Ahmet Davutoglu told a joint news conference with Italy's new Foreign Minister Giulio Terzi Friday in Istanbul. "It must open its doors to observers."

Syria's state-run SANA news agency, however, dismissed the ultimatum, declaring Friday that the Arab League had become a "tool for foreign interference" and that it was serving a Western agenda to stir up trouble in the region.

SANA also said thousands of people were demonstrating in support of the regime.

But violence continued Friday, after activists urged protesters to flood the streets to support army defectors who have sided with the opposition.

Syrian security forces fired outside mosques in Daraa province — apparently to prevent demonstrations by people leaving mosques after Friday afternoon prayers, activists said. Demonstrations were reported in Idlib province, which borders Turkey.

At least 11 people were reported killed, according to the British-based observatory while another activist group, the Local Coordination Committees said that as many as 19 were killed.

Some countries are exploring the possibility of stronger steps to force Assad's hand, with French Foreign Minister Alain Juppe calling for EU-backed humanitarian corridors to allow aid groups a way in.

Juppe called the situation in Syria "no longer tenable" and accused Assad's regime of "repression of a savagery we have not seen in a long time."

He told France-Inter radio he was in contact with partners in the United Nations, U.S. Secretary of State Hillary Rodham Clinton and the Arab League about the possibility of setting up the humanitarian corridors.

Juppe suggested that aid groups like the Red Cross could use the corridors to bring medical supplies to cities like Homs.

France, Syria's one-time colonial ruler, was the first country to formally recognize Libya's opposition in an early stage of Moammar Gadhafi's crackdown on protests. Paris played a prominent role in the NATO-led air campaign against Gadhafi's forces.

But while the European Union said protecting civilians caught up in Syria's crackdown on anti-government protests "is an increasingly urgent and important aspect" of responding to the bloodshed there, it fell short of endorsing Juppe's corridor idea.

Other countries have taken an unambiguous stance against intervention.

Last month, Russia and China vetoed a Western-backed U.N. Security Council resolution condemning the bloodshed in Syria. They have argued that NATO misused a previous U.N. measure authorizing the use of force to protect civilians in Libya to justify months of airstrikes and to promote regime change.

They expressed fears that any new resolution against Syria might be used as a pretext for a similar armed intervention.

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