|Syrian military forces have resumed attacks despite agreeing to withdraw from urban areas under an Arab League deal
Syrian tanks have opened fire in the city of Homs, activists say, killing at least five civilians and wounding dozens more, casting doubt on whether an Arab League plan can end months of bloodshed triggered by a popular uprising.
The deaths on the eve of Eid al-Adha increased to at least 80 the number of civilians reported killed in Homs since Tuesday by troops trying to crush protests against President Bashar al-Assad.
"The failure of the Arab solution would lead to catastrophic results for the situation in Syria and the region as a whole"
- Nabil Elaraby,
Arab League secretary-general
At least 22 others died on Saturday, in similar incidents across the country, according to Syrian activist groups.
Al Jazeera was unable to verify independently the reports of the deaths.
"Whole buildings have been gutted by tank fire. Bread has run out and people who get hit in the streets are dying from their wounds on the spot because no one can reach them," Samer, a local activist, said.
In a live address to Syrians on Al Jazeera television, Burhan Ghalioun, a prominent opposition figure, said the Syrian National Council, which was formed in the Turkish city of Istanbul two months ago, had asked the Arab League and UN to help protect the civilian population by sending in international human rights monitors.
"We'd not exclude any option ... and we will continue to garner international support. The regime aims to gain time from every initiative. It is wrongly betting on pushing the country into chaos and civil war," Ghalioun said.
Arab League warning
The head of the Arab League has said the organisation is seriously concerned by ongoing violence and appealed to Syria to abide by steps agreed this week with Arab states to protect civilians and set the country on the course of dialogue.
"The failure of the Arab solution would lead to catastrophic results for the situation in Syria and the region as a whole," Nabil Elaraby said in a statement from Cairo on Saturday.
To mark the Muslim feast of Eid al-Adha, Syria has freed 553 people arrested during anti-government protests while condemning the US for suggesting Syrians reject an amnesty offered to lay down their arms.
Al Jazeera's Rula Amin, reporting from Beirut, in neighbouring Lebanon, said this had not appeased the people,
"The activists are insisting that government keep its word in releasing the many thousands who have been arrested since the uprising began," she said.
The Syrian government blames "foreign-backed armed gangs" and "Islamist militants" for the violence and says they have killed 1,100 members of the security forces since the uprising began in March against 41 years of rule by Assad's family and their Baath Party.
The UN says more than 3,000 people have been killed in the crackdown.
Arab leaders have increased criticism of Assad as the killings mounted, but are cautious about the notion of major political change in the country for fear this could cause chaos, given Syria's sectarian divisions.
Syria is dominated by Assad's minority Alawite sect while Sunni Muslims form the majority.
For the same reason, together with Syria's location along fault lines of Middle East conflict, Western countries have shown no inclination for a repeat of the NATO bombardment that was key in the fall of Libya's Muammar Gaddafi.
Assad has been strengthening an alliance with Iran, started by his late father, Hafez al-Assad, while continuing his policy of avoiding confrontation with Israel on the occupied Golan Heights frontier after a 1974 ceasefire.
In-depth coverage of escalating violence across Syria
The opposition has so far rejected talks with Assad as long as violence continues and has said the only way to restore peace is for the president to step down immediately.
"How can we talk about a dialogue when Syrians cannot meet each other, express an opinion or an ideology without being in danger? These rights have to be guaranteed for participation in public issues,"Aref Dalila, a prominent dissident, said.
Dalila is an economist who was jailed for eight years after criticising a mobile phone concession that was awarded to a cousin of Assad.
State television announced on Friday amnesty to anyone with weapons if they reported to police within a week, "as long as they did not commit any crimes of killing".
The same day, security forces killed at least 19 people and wounded dozens across Syria, activists said. State television denied that any protesters were killed on Friday.
The amnesty did not appear to be part of the Arab League plan, accepted by Syria on Wednesday, under which the army would leave turbulent cities, political prisoners would go free and talks with the opposition would begin within two weeks.
Rights campaigners say tens of thousands of Syrians have been arrested since the start of the uprising, with thousands more counted as missing.