Syrian troops Thursday killed at least 25 people, including six children, in a crackdown on pro-democracy protesters in the restive cities of Hama and Homs, an activist based in Lebanon said, dpa reported.
Four soldiers died in clashes between army deserters and Syrian troops in the province of Idlib near the border with Turkey, activist Omar Idlibi said.
"Twenty-four people, including a toddler, were killed in Homs, and another civilian was killed in Hama," Idlibi told dpa.
"Some of the wounded are too scared to go to government hospitals for fear they might be arrested. So they are (being) treated in makeshift clinics," Idlibi said.
He said more than 50 people were arrested when security forces stormed the Douma and Sabqqa neighbourhoods on the outskirts of the capital Damascus.
Meanwhile, several cities in Syria went on strike, responding to a call by the opposition General Syria Revolution Committee to support the people of Homs, where security forces have reportedly killed more than 110 civilians in the past week.
Footage posted on opposition websites showed closed shops in Damascus, Hama, the southern province of Daraa and the town of Albu Kamal near the border with Iraq.
It is difficult to independently verify news from Syria, where the authorities have barred foreign journalists from reporting freely.
Syrian President Bashar al-Assad is under pressure from Arab and Western governments to end the crackdown, which the United Nations says has killed more than 3,500 people.
On Thursday, human rights group Amnesty International urged the Arab League to press Syria to allow independent monitors into the country.
"Killings and arrests of unarmed protesters and others continue to be reported on a daily basis, making a mockery of Syria's promises to the Arab League," said Philip Luther, Amnesty's acting director for the Middle East and North Africa.
An Arab diplomat in Beirut told dpa there were deep disagreements among Arab League members over how to deal with the Syrian crisis, ahead of an emergency meeting scheduled for Saturday in Cairo.
"The Arab Gulf states want the Arab League to be firm on Saturday to stop the continued bloodbath in the country," the diplomat said, on condition of anonymity.
The Arab League has accused the Syrian government of failing to implement a plan it drafted to end the months-long violence.
In Cairo, Syrian opposition politician Haytham Mana warned Thursday that failure to implement the Arab League plan would lead to "worse scenarios."