Protests have been staged in towns and cities across Syria, including the capital Damascus, a day after the government announced limited changes.
Unconfirmed reports said a number of people had been killed in at least three separate protests.
Fresh gunfire was also heard in the city of Deraa, which has become the centre of a serious challenge to the regime of President Bashar al-Assad.
Amnesty International fears 55 people have died there in the past week.
The marchers who took to the streets in Deraa on Friday had attended funerals for some of the 25 protesters killed on Wednesday.
Some of the protesters started a fire under a bronze statue of Mr Assad's father, the late President Hafez al-Assad, witnesses reported.
Another group of protesters trying to reach Deraa were killed in the nearby village of Salamen when security forces opened fire.
A government official confirmed that at least 10 protesters had died, although witnesses said up to 20 people had been killed.
In Damascus, around 1,000 were reportedly continuing a protest into Friday night, vowing to stay until their demands had been met.
Earlier, hundreds marched on King Faisal Street chanting: "Peaceful, Peaceful, God, Syria, Freedom."
This protest was broken up by security forces and many were arrested, reports say.
Another protest reported to the BBC by an eyewitness took place around al-Rifai near Qasar Sousah Square.
Supporters of Mr Assad were also staging large protests in the capital, and clashes erupted between the two sides.
In the central city of Hama, hundreds of people were said to have gathered on the city streets to chant "freedom".
In 1982, the Syrian army put down an uprising led by the Muslim Brotherhood in Hama. Rights groups believe that tens of thousands of civilians were killed when large parts of the city were destroyed in the military assault.
In Tall, witnesses quoted by the Reuters news agency said about 1,000 people had rallied to show their support for the Deraa protesters, and were chanting slogans denouncing members of the ruling Assad family.
Demonstrations which ended in violence were also reported in the cities of Latakia and Homs. One person was killed in each place, the Associated Press news agency quoted an activist as saying.
There were also protests in Banias and Dahel, AFP reported.
On Thursday, the Syrian government said it would consider political reforms, including the possible ending of emergency laws introduced in 1963.
The government also said it would put on trial those suspected of killing several protesters in Deraa.
Mr Assad later ordered the release of everyone arrested during the "recent events", state media said.
Presidential spokeswoman Bouthaina Shaaban blamed outside agitators for whipping up trouble, and denied that the government had ordered security forces to open fire on protesters.
But she said this "did not mean mistakes had not been made".
'Appalling and brutal'
UN Secretary-General Ban Ki-moon has telephoned Mr Assad to urge restraint and underline Syria's obligation to respect the fundamental rights of its citizens.
In the US, White House spokesman Jay Carney said Washington was deeply concerned at what was happening.
"We strongly condemn the Syrian government's attempts to repress and intimidate demonstrators," Mr Carney said.
Amnesty also condemned the treatment of demonstrators.
"The excessive force apparently again being used by security forces is the latest example of the Syrian authorities' appalling and brutal response to recent dissent, and make their pledge to investigate the violence sound rather hollow," said spokesman Philip Luther.
"If the words we heard from the Syrian government yesterday are to mean anything, they must immediately issue clear orders to restrain the security forces to prevent further loss of life."