Syria's president, who is fighting an Arab Spring-inspired revolt, called a constitutional referendum that would effectively end nearly 50 years of single-party rule, state media said.
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 must be a Muslim man and may 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, said the constitution would usher in a "new era" for Syria, SANA state news agency reported.
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.
The SNC, the main opposition group which is hoping to win recognition abroad as Syria's legitimate authority, has agreed that current leader Burhan Ghalioun will remain in place for another three months, a group spokeswoman said late Wednesday.
Ghalioun has served as leader since the group's founding last October to oppose the Assad regime.
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Ghalioun is an academic who has been living in exile in France for more than 30 years. A leftist Arab nationalist, he was seen as the person who could bring together the council's various factions, from Islamists and nationalists to liberals and independents.
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.
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.
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.
In Hama, just north of Homs, 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 36 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 Lavrov to change tack when the two meet in Vienna on Thursday by arguing that Moscow is becoming isolated internationally because of its stance.
Diplomats said Russia has asked for a number of changes to the draft General Assembly resolution.
One of the amendments Russia wants is on a paragraph referring to the Arab League plan of January 22 that calls for Assad to hand over power to his vice president. Moscow opposes any change to the regime imposed from outside.
Another change would link the return of Syrian troops to their barracks to an "end of attacks by armed groups against state institutions." Russia has insisted on acknowledging an opposition role in the violent unrest.
Russia also wants the opposition "to dissociate themselves from armed groups engaged in acts of violence," and not mention Syrian government abuses against civilians.
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.