Syria continued to defy mounting international pressure to halt attacks on civilian protesters Friday as Turkey and France suggested they are not ruling out the possibility of military intervention if the violence continues to escalate.

Human rights groups and activists said Syrian security forces killed at least 17 protesters across the country after tens of thousands of people poured into the streets yet again after Friday prayers to demand the ouster of President Bashar al-Assad.

The shootings came a day before the expiration of a deadline, issued by the Arab League on Wednesday, for Syria to agree to admit teams of human rights monitors. Shortly before the ultimatum, Syria’s foreign minister, Walid Moallem, had said that monitors would be allowed into the country under the terms of an Arab peace plan that Syria accepted earlier in the month but then proceeded to ignore.

The Arab League’s secretary general, Nabil Elaraby, said, however, that Syria had requested unspecified amendments to the proposal, making it unclear whether it had in fact agreed. In a statement issued by his office, Elaraby said the League was “studying” the amendments.

Activists are not confident that monitors will help resolve the violence even if they are admitted. There are still many issues to be resolved, including the question of where they would be allowed to go, whether they will be permitted to move freely and which names would be approved for visas, said Wissam Tarif, a longtime Syrian human rights activist with the advocacy group Avaaz whose name is on the proposed list of monitors.

“I don’t think the Syrians are serious. I think they are bluffing,” he said. “This is a game they are playing.”

Syria was suspended from the Arab League on Wednesday after its failure to comply with the Arab peace plan and could face potentially crippling Arab economic sanctions if it does not agree to accept the monitors by Saturday.

The largely symbolic suspension was accompanied by more serious measures that suggest most Arab states have decided that it would be better to start planning to replace Assad’s government than risk seeing Syria’s spiraling unrest evolve into a full-scale conflict that could engulf the region.

The Arab League is expected to launch a formal dialogue next week with members of the Syrian opposition in Cairo and is reaching out to the U.N. Security Council to secure a broader condemnation of the government crackdown that has so far killed more than 3,500 civilians, according to U.N. figures. The Syrian government says at least 1,150 members of the security forces also have been killed in an uprising it portrays as the work of “armed gangs.”

A U.N. resolution condemning the violence was vetoed by China and Russia earlier in the year, and there is still no sign that they would be prepared to revise their stand in light of the Arab shift against Assad. For now, the only specific measures under discussion are sanctions.

But in Ankara, Turkish Foreign Minister Ahmet Davutoglu and French Foreign Minister Alain Juppe indicated that military intervention is not being ruled out.

Davutoglu told a joint news conference it was Turkey’s “hope” that the Syrian crisis would be resolved without military intervention. “However, if the massacres of civilians continue, we won’t be indifferent to that, whether in Syria or any other country,” he said.

Juppe said France would not countenance a unilateral intervention, an apparent reference to Turkey, a NATO member bordering Syria that is the country most likely to play a leading role in any regional initiative to offer military support to the protest movement. “If an intervention is implemented, the decision should be made by the United Nations,” he said.

Western powers, including the United States, have made it clear they have no intention of getting militarily involved in the volatile and strategically located country.

But as the Syrian security forces have sought relentlessly to crush the anti-government movement, Syrian protesters have begun calling for outside help in the form of a no-fly zone to facilitate the creation of a rebel army. A senior leader of Syria’s outlawed Muslim Brotherhood told a press conference in Istanbul on Thursday that Syrians “will accept Turkish intervention,” according to comments quoted by Reuters.

Increasingly, protesters are throwing their support behind the fledgling Free Syrian Army, a group formed by defected soldiers in Turkey that claims it is mounting guerrilla-style attacks against the Syrian security forces.

A video posted on YouTube on Thursday suggests that the self-proclaimed rebels are acquiring the capacity to stage effective operations. The footage depicts a tank being blown up in an ambush in the Bab Amro neighborhood of the central city of Homs.