Syrian activists say at least 15 people were killed in a crackdown on dissent across Syria Saturday, as and Arab League deadline neared for Damascus to end the bloodshed.

The activists said most of the deaths occurred in fresh raids by security forces, while at least two army deserters died in clashes in Homs.

The state-run SANA news agency said authorities raided the “hideouts of terrorists groups” Saturday and arrested more than 140 “wanted men.”

The Arab League has set a deadline of Saturday midnight, local time, for Syria to end the crackdown or risk sanctions. A week ago, the 22-member bloc has suspended Syria's membership.

The league's plan also calls for Damascus to allow in teams of observers to monitor its compliance. On Friday, Syria agreed to the plan “in principle,” but had submitted unspecified amendments that were under review.

Meanwhile, Turkish Prime Minister Recep Tayyip Erdogan said Syria was responsible for the deteriorating relations between the two countries. He accused Syria of not fulfilling promises to Turkey, the Arab League and to the world for reform or to stop the bloodshed

Israeli Defense Minister Ehud Barak acknowledged that Israel would benefit from Syrian President Bashar al-Assad's downfall, saying it would mean less support for militant groups like Hezbollah and Hamas.

Damascus has been facing mounting international pressure to end the unrest that the U.N. says has resulted in more than more than 3,500 deaths.

On Friday, U.S. Secretary of State Hillary Clinton expressed concern that Syria could slide into civil war.

Meanwhile, British Foreign Secretary William Hague said he would meet with Syrian rebel leaders in London Monday. Hague has condemned the violence and called for Mr. Assad to step aside.