A prominent Syrian opposition figure says the country is "a bomb, ready to explode" as protesters demand freedom and an end to president Bashar al-Assad's "cancerous regime".

Tens of thousands of Syrians have once again poured onto the streets of the city of Daraa in protest after security forces were accused of storming and massacring people in the city's main mosque on Wednesday.

Witnesses say security forces opened fire on hundreds of youths at the northern entrance to Daraa on Wednesday afternoon, in a dramatic escalation of nearly a week of protests in which at least 44 civilians have been killed.

As anger mounts around his country, Mr Assad has made a rare public pledge to look into granting Syrians greater freedom.

But a prominent opposition figure has told The World Today the concessions do not go far enough.

Haitham Maleh, who was released from prison earlier this month under an amnesty for older political prisoners, says his countrymen are ready for a revolution.

The 80-year-old lawyer is one of Syria's most prominent human rights campaigners, and he has suffered for it.

"They punished me many times, yes. I spent eight years and a half of my life in jails," Mr Maleh said.

Released from his latest prison sentence as part of government concessions in early March, Mr Maleh says the Syrian government has been promising change - and failing to make it - for 10 years.

He says Syria is about to explode.

"We are like a bomb, it's nearly to explosion," he said.

"They said that they will do something. We heard this speech since 10 years and they did not do anything on the ground."

Mr Maleh says Syria has 15 intelligence services which serve to repress the people, and its jails are full of political prisoners.

He says he does not expect anything to change if Mr Assad remains. He compares the regime to a cancer.

"Through this regime nothing will be changed. This regime [is] like cancer and they want no medical. It needs surgery," he said.

He says a full scale revolution is needed across all Syrian cities - not just Daraa.

"This is the beginning. Like the snowball, it became bigger and bigger through the time," he said.

Danger looms

The Syrian regime appears desperate to make more concessions.

Last week, it announced the term for military service was being cut by three months. Now there is talk of a possible end to 48 years of emergency rule; even laws to provide for media freedoms and allow other political movements.

The government has also authorised a 20 to 30 per cent pay rise for public servants across the country.

But Mr Maleh says it is not enough.

"It's up to the people. I think if we will have the same situation like Egypt or Tunisia ... everything will be changed," he said.

But he says he hopes Syria does not head down the same path as Libya.

"I don't like to see blood like Libya. In Libya there is big, big, bad things," he said.

The Foreign Affairs Department is now warning Australians to reconsider travelling to Syria because of the recent violent clashes.