Syrian pro-democracy activists say security forces have opened fire on protesters in several parts of the country, leaving at least eight people dead.
The deaths came as thousands rallied after Friday prayers against the Syrian government.
Three people died from bullet wounds in Douma, near the capital, Damascus, while an elderly man and two others were killed in the city of Homs, where security forces opened fire against protesters, the UK-based Syrian Observatory for Human rights (SOHR) said.
Two other fatalities were reported following protests in the coastal city of Latakia and in the suburbs of Hama.
Al Jazeera's Rula Amin, reporting from Beirut in neighbouring Lebanon, said the protests are still going strong, even after six months of demonstrations.
"The government is continuing its crackdown. The opposition insists on the fall of the regime and the government insists it will end the wave of protests."
In the east of the country four assailants reportedly shot dead Mishaal al-Tammo, a prominent Kurdish opposition figure, and wounded his son.
It was not clear who was behind the attack. Tammo, who was released from jail earlier this year, was a critic of President Bashar al-Assad. But he had also angered powerful Kurdish parties by scolding them.
For its part, the Local Co-ordination Committees (LCC), an opposition activists' network, reported demonstrations on Friday calling for the end of the government in the Damascus neighbourhood of Qabun, which was rocked by shootings the previous Friday.
And a curfew was imposed on the flashpoint town of Rastan, 20km north of Homs, where security forces surrounded mosques in a bid to prevent people from attending Friday prayers, a rallying point for protests, the LLC said.
Pro-democracy activists had called for fresh Friday demonstrations under the banner: "The Syrian National Council is our representative, mine, yours and that of all Syrians."
Elsewhere, activists said Syrian troops pursued armed defectors near the border with Turkey, setting off clashes in which 12 people died.
The clashes with defectors took place after troops stormed villages on Thursday west of Jabal al-Zawiya, near the Turkish border, the SOHR said.
"Seven soldiers and five deserters or civilians were killed in the clashes," the group said, adding that 32 people had been wounded.
Activists said four people died in similar clashes earlier in the week between Syrian troops and deserters who had defected after refusing to fire on anti-government protesters - also near the Turkish border.
An army officer who has taken refuge in Turkey, Colonel Riad al-Asaad, claims to have established an opposition armed force called the "Syrian Free Army", but its strength and numbers are unknown.
Analysts say that the unrest in Syria, which began in mid-March as peaceful protests against Assad's autocratic rule, is becoming increasingly armed in response to the relentless killing of protesters by security forces.
On the diplomatic front, Dmitry Medvedev, the Russian president, said Assad will have to give up power if he fails to implement reforms acceptable to the opposition.
"It's one more friend of President Bashar al-Assad who is warning him and adding more pressure on the government in Damascus," Al Jazeera's Amin said.
"Obviously the Russians have used their veto to block any UN resolution condemning Syria, but today [Medvedev] was very blunt ... it was the starkest warning from the Russians so far to their friend in Damascus."
Diplomats in Brussels said the EU was preparing to target a Syrian commercial bank and 29 Iranians accused of human-rights violations in fresh sanctions to be announced in the coming days.
In-depth coverage of escalating violence across Syria
One EU diplomat named the bank as the Commercial Bank of Syria, targeted by a US assets freeze in August.
The 27-nation bloc last month banned the delivery to Syria's central bank of bank-notes and coins produced in the EU, in a seventh round of sanctions designed to step up economic pressure on Assad's government.
The planned new measures come after European nations failed in their attempt to push a resolution through the UN Security Council on Tuesday.
It had called for "targeted measures" against Damascus if it did not halt its crackdown.
The resolution was vetoed by Russia and China, provoking the fury of the US and EU powers.
Syria, which maintains that the regime's opponents are armed gangs and terrorists trying to sow chaos, hailed the vetoes as "historic".