Tank fire killed at least 13 civilians and wounded dozens in the besieged Syrian city of Homs on Saturday, activists and residents said, casting doubt on whether an Arab League plan can end months of bloodshed touched off by a popular uprising.
In Cairo, the Arab League chief said the organisation was seriously concerned by ongoing violence and appealed to Damascus to abide by steps agreed this week with Arab states to protect civilians and set Syria 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, Arab League Secretary-General Nabil Elaraby said in a statement.
The deaths in Homs, on the eve of the main Muslim feast of Eid al-Adha, increased to at least 89 the number of civilians reported killed in Homs since Tuesday by troops trying to crush protests against President Bashar al-Assad and an incipient armed uprising.
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, said Samer, a local activist.
In an address to Syrians aired live on al-Jazeera television, prominent opposition figure Burhan Ghalioun said the Syrian National Council, which was formed in Istanbul two months ago, had asked the Arab League and United Nations to help protect the civilian population by sending in international human rights monitors.
We de 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, said Ghalioun, who headed a National Council delegation that met Elaraby this week.
The government blames Islamist militants and foreign-backed armed gangs for the violence and say 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 United Nations says more than 3,000 people have been killed in the crackdown.
Arab leaders have ramped up 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 appetite 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 Shi'ite Iran, started by his late father, President Hafez al-Assad, while continuing his policy of avoiding confrontation with Israel on the occupied Golan Heights frontier after a 1974 cease-fire.
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, said dissident Aref Dalila, a prominent economist who was jailed for eight years after criticising a mobile phone concession that was awarded to a cousin of Assad.
On Friday state television announced an 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 had been 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.
The official news agency said 553 detainees were released on Tuesday on the occasion of the Eid feast. Rights campaigners say tens of thousands of Syrians have been arrested since the start of the uprising, with thousands more counted as missing.
Elaraby expressed serious concern over the continuing violence and appealed to Syria to take immediate steps to protect civilians. He said the League wanted to safeguard Syria's security and avoid foreign intervention.
Elaraby said he had received reports in the past two days from Syria's League representative about armed groups involved in violent acts and sabotage in Homs, Hama and other areas.
The Syrian Observatory for Human Rights said three protesters were shot and wounded by security forces in the southern town of Dael on Saturday. It added that four pro-Assad militiamen were killed in fighting with army defectors near the city of Khan Sheikhoun north of Homs.
Several thousand mourners marched in Khan Sheikhoun in a funeral for a 20-year-old soldier and a policeman who had refused to shoot at protesters and were summarily executed, the Observatory said.
The people want the execution of the President, chanted the crowd, according to a YouTube video.
Syria does not allow access by most foreign journalists, making independent verification of events impossible.
U.S. State Department spokeswoman Victoria Nuland reacted dismissively when asked if she thought Syrians should participate in the amnesty, saying: I wouldn't advise anybody to turn themselves in to regime authorities at the moment.
She also accused the Syrian government of failing to follow through on the Arab League plan and said the United States had no confidence that it would. We have a long, deep history of broken promises by the Assad regime, she told reporters.
The Syrian government condemned irresponsible statements ... that aim to ignite sectarian strife and support the killings and terrorism being practised by the armed groups against Syria's citizens.
In Homs, the bombardment was concentrated on Bab Amro, a poor residential district several kilometres (miles) from the city centre, where insurgents and an increasing number of army defectors have taken refuge, residents said.
The humanitarian situation in Bab Amro has become horrific. Inhabitants are reporting a total siege and dwindling food and medicine supplies, exiled dissident Rami Abdelrahman told Reuters by telephone from Britain on Saturday.
Tensions have also grown in Homs between members of its Sunni majority and minority Alawites after reported tit-for-tat sectarian killings this week.
(Additional reporting by Edmund Blair in Cairo, Editing by Mark Heinrich)