Syrian troops killed at least one civilian in overnight raids in the city of Homs, activists said, a day after the authorities held a "national dialogue" meeting boycotted by the opposition.
The Syrian Observatory for Human Rights said on Monday that 20 people were injured as residents tried to take shelter from armoured vehicles firing machineguns on densely populated neighbourhoods.
Residents said the raids were the heaviest since the military stormed the central city, Syria's third largest, two months ago to try to crush street protests against President Bashar al-Assad's rule.
"Military raids and house-to-house arrests have become routine after protests," said a resident of Homs' Bab Sbaa district. "But this time they did not stop shooting all night in the main neighbourhoods."
Syria has barred most independent media from operating inside the country, making it difficult to verify accounts of activists and authorities.
'National dialogue' boycotted
On Sunday, Syria had opened a "national dialogue" that it hailed as a step towards multi-party democracy after five decades of Baath party rule.
The government said the discussions would include a new media law, but the credibility of the talks appeared to have been undermined by an opposition boycott.
Rula Amin, Al Jazeera's correspondent, said: "We have to remember that whoever is there came on an invitation from the government.
"The opposition figures who we spoke to, said that we heard very nice words but what we want to see is actions and deeds. Word wise, this is unprecedented, beyond that, this meeting will not bring any results.
"Before it is seen as [a] serious [attempt], they have to see action on the ground, the [security] forces have to be withdrawn. As otherwise everything that is said is meaningless."
Delegates at the two-day meeting in Damascus, the capital, observed a minute's silence in memory of the "martyrs" before the national anthem was played.
"We are going to hold a comprehensive national dialogue during which we will announce Syria's transition towards a multi-party democratic state in which everyone will be equal and able to participate in the building of the nation's future," Faruq al-Shara, Syria's vice president, said in his opening address.
Al-Assad announced the dialogue in a keynote speech on June 20, only his third address since unprecedented protests against his rule erupted in mid-March.
The government said that delegates would be invited to discuss a wide range of reforms, including amending clause eight of the constitution which enshrines the leading role of the Baath party in Syrian political life.
Delegates were expected to include some independent MPs as well as members of the Baath party, in power since 1963.
But opposition figures said they would boycott the meeting in protest at the government's continued deadly crackdown on dissent.
Since the protests began, the government has killed more than 1,300 civilians and arrested at least 12,000, human rights groups say.
"If you hear the protesters, they dismissed these talks and they say that they do not represent them. But there will be people who will say that still this is progress," our correspondent said.
"The test is how the government will proceed from here and how these words will be translated into action.
"We heard very harsh statements in that room, even by people who are pro-government. Some said that the security system has to be dismantled. These are major transformations, for people to speak about, and covered by state television."
Razan Zeitouneh, a Syrian human rights lawyer in Damascus, told Al Jazeera that the dialogue was meaningless as long as the security crackdown continued simultaneously.
"How can you expect such a meeting, which is called a dialogue, while at the same time, at the same moment that this meeting is held there is a funeral of people who got killed during last few days in Homs and other cities. It's impossible that ... you want to talk to people from one side, and you continue killing them and arresting them all the time on the other side," she said.
She said that the dialogue was a result of "international pressure" and was not meant to address the concerns of Syrians.
"I should not be at the table with the same ... regime who committed all these crimes. I cannot be," she said.