Syria's president, who is fighting an Arab Spring-inspired revolt, on Wednesday called a constitutional referendum that would effectively end nearly 50 years of single-party rule, state media said.
An image grab taken from a video uploaded on YouTube apparently shows smoke billowing from the Baba Amro neighbourhood of the flashpoint city of Homs.
A day after rejecting UN allegations of crimes against humanity, Bashar al-Assad called the referendum for February 26, in a move aimed at placating growing global outrage over the bloodshed.
The proposed charter drops Article 8, which declared the ruling Baath Party as the "leader of the state and society," allowing for a multi-party system, state television said.
The president, who must be a Muslim man, can serve a maximum of two seven-year terms, although it is unclear if this would apply to Assad, who is already in his second term.
In April, Assad scrapped emergency rule in force since 1963, when the Baathists took power in a coup d'etat. But he has repeatedly promised reforms that have failed to materialise since the uprising erupted in March.
The embattled 46-year-old president, who succeeded his late father Hafez in 2000, has said the constitution would usher in a "new era" for Syria, SANA state news agency said.
"When the new constitution is approved, Syria will have passed the most important stage" of reforms, bringing a "brilliant future for next generations," Assad was quoted as saying.
The United States dismissed the move as laughable. Russia, a major weapons supplier to Damascus, welcomed it.
White House spokesman Jay Carney said "it's actually quite laughable -- it makes a mockery of the Syrian revolution.
"Promises of reforms have usually been followed by an increase in brutality and have never been delivered upon by this regime since the beginning of peaceful demonstrations in Syria."
Russian Foreign Minister Sergei Lavrov said "we certainly believe a new constitution to end one-party rule in Syria is a step forward. It is a welcome idea and we hope the constitution will be adopted."
The opposition Syrian National Council is likely to reject the constitution, given that one of its main guiding principles is "to overthrow the regime using all legal means."
Regardless, the proposed charter rules out most of the opposition as it bans religious parties and dual nationals, preventing the SNC, which includes the Muslim Brotherhood, and most of its leadership from running for office.
Analysts said the referendum was too little, too late and fell short of what was required to end the uprising inspired by similar movements that last year overthrew authoritarian leaders in Egypt, Libya and Tunisia.
"It's good that the regime at any point talks about reform or fundamental change, but... holding a referendum amid a civil war between the government and its people is unacceptable," said Paul Salem of the Carnegie Middle East Centre.
Assad's decision came as activists said troops stormed the central city of Hama and stepped up assaults nationwide, defiant in the face of mounting Arab and Western peace efforts.
Amnesty International said more than 607 people had been killed in Syria, including 45 children, since February 3, when government troops launched a major assault on the flashpoint central city of Homs.
"The latest surge in casualties chimes with remarks by the UN High Commissioner for Human Rights that the international community's failure to act had 'emboldened' the Syrian military assault," the rights watchdog said in a statement.
Assad's forces appear to have refrained from using air power to crush armed rebels to avoid a no-fly zone being imposed over the country.
On the ground, however, troops launched an assault on the city of Hama, just north of Homs, where loud blasts could be heard in the Hamidiyeh and other neighbourhoods, said the Syrian Observatory for Human Rights.
Rami Abdel Rahman, head of the Britain-based group, said ongoing clashes had killed at least 33 people, including 12 soldiers. The majority were killed in fighting in Al-Atareb, northwestern Aleppo province.
China and Russia have faced a barrage of criticism for blocking a second UN Security Council resolution condemning the Assad regime.
As diplomats said they would seek to condemn the violence at the UN General Assembly on Thursday, France said the world body should consider setting up "humanitarian corridors" to get aid to Syrians caught up in the violence.
French Foreign Minister Alain Juppe also said he would try to convince his Russian counterpart to change tack, when the two meet in Vienna on Thursday, by arguing that Moscow is becoming isolated internationally because of its stance on Syria.
But Lavrov on Wednesday took a swipe at countries wanting to isolate President Bashar al-Assad's regime, saying that shutting Damascus out of talks to end the violence would be a "mistake."
Rights groups say more than 6,000 people have been killed since regime forces began cracking down on democracy protests launched 11 months ago to the day.