The Syrian government and regime opponents blamed each other Wednesday for the murder of a nuclear engineer, the latest death among scientists in the flashpoint city of Homs.
Meanwhile, Russia balked at Europe's effort to get the UN Security Council to threaten sanctions against Syria, saying it encourages violence.
And despite news of still more killing in the six months of violence that has claimed the lives of some 2,700 people, Syrian President Bashar al-Assad was quoted as saying the "troubling events have ended".
The Britain-based Syrian Observatory for Human Rights said "nuclear engineer Aws Abdel Karim Khalil was killed this morning (Wednesday) by unknown attackers".
State news agency SANA said Khalil was "shot in the head by a terrorist group as his wife was driving him to work" at the university.
In the same city, unidentified attackers killed Mohamed Ali Aqil, deputy rector of the architecture faculty at Al-Baath University, and Nael Dakhil, director of the military petrochemical school, on Tuesday.
And on Sunday, a surgeon at Homs' general hospital, Hassan Eid, was gunned down as he got into his car.
The authorities said the four were killed by "terrorists".
Al-Ghad, an alliance of anti-regime activists, accused the government of "killing the scientific figures in Homs, trying to repeat the scenario of murders" in the 1980s, when Assad's father, Hafez, carried out a deadly campaign against the Muslim Brotherhood.
Observatory chief Rami Abdel Rahman said "we firmly condemn the murder of these four persons close to the regime", and a statement from the group called on "everyone to denounce and stop extremists from committing such acts of violence".
Activists say Khalil and Eid belonged to the Alawite sect of Islam to which Assad also belongs, while Aqil was a Shiite Muslim and Dakhil a Christian.
Al-Ghad highlighted the "responsibility of the regime for Syrian blood that is flowing, and which has failed to provoke confessional discord in Homs and is again trying to arouse it by targeting these scientific personalities".
Meanwhile, the Observatory said three deserting soldiers were killed and an officer died of wounds sustained in fighting between loyalist and dissident troops in Rastan, near Homs.
Meanhile, the Observatory said the bodies of two people arrested a number of days ago were delivered to the military hospital in Homs.
And a man wounded earlier this month when he was arrested in a town west of Damascus reportedly died in prison.
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But Assad reportedly said stability had returned to the country, in a meeting with former Lebanese premier Selim Hoss.
"The painful events are over, thank God," Hoss quoted him as saying.
"There is a return to stability in Syrian cities that have been the scene of these events," he added, saying "Syrian authorities are monitoring the situation to preserve the well-being of the Syrian people".
On the diplomatic front, Russia went on the offensive against Europe's effort to get the UN Security Council to threaten sanctions against Syria
The council is set to discuss Wednesday rival draft resolutions drawn up by Britain, France, Germany and Portugal, on the one hand, and Russia on the other.
The European proposal drops demands for immediate sanctions but wants to threaten Assad with action if he does not end his deadly crackdown on protests.
Russia opposes any hint of sanctions, and the latest version of its draft resolution seeks to condemn violence by all sides in Syria.
Russian Ambassador Vitaly Churkin called the European proposal "a continuation of the Libya policy of regime change". China and Russia have accused NATO of using UN resolutions on Libya to force out Moamer Kadhafi and say they fear new military action in Syria.
"Let's face it, we have heard statements in various capitals describing what is legitimate and what is not, and we think that this line of thinking and speaking is encouraging violence in Syria," Churkin told reporters.
He said the Russian resolution "is something which if adopted by the council will encourage the political process in Syria and will help stop violence".
In Washington, State Department spokeswoman Victoria Nuland said the United States was working with its EU partners on the resolution, which she said should have "consequences" for the Syrian regime without actually mentioning sanctions.
"We want a resolution with teeth. We want a resolution that makes it absolutely clear to the Assad regime that the violence needs to end," Nuland told reporters.
When asked if her calls for "consequences" meant sanctions, Nuland replied: "tightening .... the economic and political noose on the Syrian regime".
The EU and the United States have already imposed a series of sanctions on the Assad regime, and those measures are already having an effect.
Damascus surprised the world last week by announcing the temporary suspension of imports of products subject to tariffs of more than five percent.
The curbs have sent prices of cars, furniture, clothes, household appliances and certain foodstuffs rocketing, with consumers complaining they will have to make do with locally produced goods.
Syrian central bank governor Adib Mayaleh told AFP the import restrictions would save Syria $6 billion (4.4 billion euros) annually.
The unrest rocking the country has slowed economic activity, with analysts predicting negative economic growth in 2011 as a result of a decline in tourism and investment.