Syrian security forces stormed the central city of Homs overnight, a day after the a government-proposed round of talks was boycotted by prominent opposition groups, DPA reported.
The Syrian Observatory for Human Rights said one person was killed and 20 injured as security forces in armoured vehicles fired on several neighbourhoods in Homs.
The vehicles swept into the Bab al-Sibaa neighbourhood amid heavy shooting, the Local Coordination Committees of Syria (LCC) said on its online group.
Monday's operation is the heaviest on Syria's third largest city since security crackdown on anti-government protests began in the country.
Heavy gunfire was also heard in several other districts in the city, which is under curfew while electricity is cut from main streets, the LCC added.
Human rights groups say that more than 1,400 civilians and 350 security personnel have been killed, while at least 12,000 have been arrested since protests erupted in March, calling for greater reforms and the ouster of President Bashar al-Assad.
The "national dialogue" proposed by al-Assad, which began in Damascus Sunday, was boycotted by prominent opposition groups urging the government to halt the crackdown against demonstrators first.
They also demand that the government allow peaceful protests, release all political prisoners and permit foreign media to cover the protests freely.
The meeting, which will resume its sessions on Monday, discusses constitutional amendments and the laws governing elections, media and the creation of political parties other than the ruling Baath party.