Security forces opened fire at one of the funerals for scores of people killed in the country's bloodiest pro-democracy protests in the Damascus suburb of Douma, wounding three people, witnesses said.

Tens of thousands of Syrians demanded the overthrow of President Bashar al-Assad on Saturday at the funerals.

They also fired on people seeking to join mass funerals in the southern village of Izra'a, where witnesses said at least 12 funerals were taking place, with mourners chanting "Bashar al-Assad, you traitor! Long live Syria, down with Bashar!"

"There was heavy volley of gunfire in our direction as we approached Izra'a to join the funerals of martyrs," one witness from the southern city of Deraa who came to attend the burials in Izra'a told Reuters.

Two activists said on Saturday at least 100 people were killed during Friday's protests. A group of activists coordinating the demonstrations had said previously that regular forces and gunman loyal to Assad shot dead at least 88 civilians on Friday.

The demonstrators were killed in areas stretching from the port city of Latakia to Homs, Hama, Damascus and the southern village of Izra'a, it said.

Friday was by far the bloodiest day in more than a month of demonstrations demanding political freedoms and an end to corruption in the country of 20 million people.

Damascus was tense on Saturday and many people stayed indoors, an activist told Reuters from the capital.

"We are worried that during the funerals more blood will be spilt which will provoke more protests and more death," he said.

"This is becoming like a snowball and getting bigger and bigger every week. Anger is rising, the street is boiling."

US President Barack Obama condemned Friday's violence and accused Assad of seeking help from Iran.

"This outrageous use of violence to quell protests must come to an end now," Obama said in a statement. "Instead of listening to their own people, President Assad is blaming outsiders while seeking Iranian assistance in repressing Syria's citizens...."     France's Foreign Ministry said Paris was "deeply concerned".

"Syrian authorities must give up the use of violence against their citizens. We again call on them to commit without delay to an inclusive political dialogue and to achieve the reforms legitimately demanded by the Syrian people."

Those killed were among tens of thousands of people who have taken to the streets of cities and rural areas across Syria calling for political reform, demands which have hardened over recent weeks.

Activists demand wider reforms

Friday's protests went ahead despite Assad's decision this week to lift the country's hated emergency law, in place since his Baath Party seized power 48 years ago.

A statement by the Local Coordination Committees said the end of emergency law was futile without the release of thousands of political prisoners -- most held without trial -- and the dismantling of the security apparatus.

In their first joint statement since the protests erupted last month, the activists said the abolition of the Baath Party's monopoly on power and the establishment of a democratic political system was central to ending repression in Syria.

Aided by his family and a pervasive security apparatus, Assad, 45, has absolute power, having ignored demands to transform the anachronistic autocratic system he inherited when he succeeded his late father, President Hafez al-Assad, in 2000.

Friday's violence brings the death toll to more than 300, according to rights activists, since the unrest which broke out on March 18 in the southern city of Deraa.

Protests swept the country on Friday, from the Mediterranean city of Banias to the eastern cities of Deir al-Zor and Qamishli. In Damascus, security forces fired teargas to disperse 2,000 protesters in the district of Midan.

Amnesty International said Syrian authorities "have again responded to peaceful calls for change with bullets and batons".

"They must immediately halt their attacks on peaceful protesters and instead allow Syrians to gather freely as international law demands," said Malcolm Smart, Amnesty International's Middle East and North Africa director.

Syrian television said eight people were killed and 28 wounded, including army personnel, in attacks by armed groups in Izra'a. It said an armed group had attacked a military base in the Damascus suburb of Muadhamiya. – Reuters