Army defectors ambushed a Syrian security patrol Tuesday killing seven in revenge for a raid that cost 11 civilian lives, activists said, as the UN estimated more than 5,000 have died in the crackdown.
State media said Syrian border guards shot dead two "terrorists" from Turkey, in other violence after a UN Security Council meeting at which Western nations stepped up pressure to condemn the deadly campaign against dissent.
At the meeting, UN rights chief Navi Pillay gave the latest death toll -- amounting to a jump of 1,000 in less than two weeks -- as she appealed to the Council to launch a crimes against humanity case.
Pillay's private briefing to the 15-nation council -- where Russia and China blocked a resolution condemning Assad in October -- heightened divisions over how to respond to the Syrian troubles.
She told reporters she had given the new toll of more than 5,000 dead -- including some 300 children -- and recommended the crackdown by President Bashar al-Assad's regime be referred to the International Criminal Court.
"The widespread and systematic nature of the killings, the detentions and the acts of torture -- I felt that these acts constituted crimes against humanity," said Pillay.
The "intolerable" situation in Syria -- where more than 14,000 have been detained -- has seen 12,400 people flee into neighbouring countries since protests erupted in March, she said.
"Inaction by the international community will embolden Syrian authorities, and ensure perpetrators go unpunished," said Pillay.
The Security Council meeting came as Western nations ramp up pressure to condemn Assad's campaign.
"I think it is necessary that those countries in the Security Council which are still hesitating change their mind," German Foreign Minister Guido Westerwelle said after meeting Pillay.
France's UN envoy said the council was "morally responsible" for the daily deaths by staying silent.
But Russia, an ally of Assad's Syria, said Western accusations it was blocking UN action condemning the crackdown were "immoral" because the West was refusing to put pressure on armed rebel groups.
"There are those who refuse to put pressure on the armed, extremist part of the opposition and are at the same time accusing us of blocking the UN Security Council's work. I would call this position immoral," Foreign Minister Sergei Lavrov said in televised comments.
Amid the diplomatic wrangling, the death toll continued to mount on Tuesday.
"Seven security force members were killed in an ambush by deserters on a convoy patrolling the Idlib-Bab al-Hawa road in response to the martyrdom of 11 civilians this morning," the Observatory said.
The 11 died when they were attacked by security forces and pro-regime Shabiha militiamen in two villages of northwestern Idlib province, it said earlier.
"Eleven people were killed and dozens others wounded Tuesday by gunfire from security forces and the Shabiha in the areas of Maarret Masrin and Kfar Yahmul," said the Observatory.
And state-run SANA news agency said border guards shot dead two "terrorist" infiltrators who were attempting to enter Syria from Turkey.
"Border guards' forces in Idlib today foiled an infiltration attempt by an armed terrorist group into the Syrian lands" in Idlib province, said SANA, adding they killed two out of the 15 "terrorists."
Ankara denied it was allowing attacks to be carried out on Syrian forces from its territory.
"Turkey never allows any attacks against other countries and neighbours from its soil," a Turkish diplomat told AFP, requesting anonymity.
Syria on December 6 reported its forces thwarted a similar infiltration bid by "armed terrorist groups" in the same area, saying an unspecified number of the 35 gunmen were wounded and the rest fled back to Turkey.
The Turkish diplomat said on Tuesday that his country now hosts 8,525 Syrians who have now fled across border to escape the crackdown, up from 7,500 refugees previously.
Colonel Riyadh al-Asaad, who heads the Free Syrian Army, is based in a Turkish border camp and, unlike some other dissidents, has called for foreign air strikes.
In restive Homs province, meanwhile, security forces shot dead two civilians including a 60-year-old man, activists said, as a blast tore through a gas pipeline near Rastan, according to SANA, which blamed "terrorists."
Homs, one of the main hubs of the unprecedented demonstrations against Assad's regime, has been besieged by security forces and loyalist militias for months.
The explosion is the fourth reported attack on energy infrastructure since the outbreak of the pro-reform protest movement in mid-March, following two similar incidents around Homs, and one in oil-rich Deir Ezzor province.
Britain, France, Germany, Portugal and the United States are waiting for the result of Arab League meetings on Syria in coming days to decide their next UN move, diplomats said.
Russia's UN ambassador Vitaly Churkin said that since the council passed a statement on Syria on August 3, events had seen the West "switch gears and turn into regime-change mode, discouraging dialogue."
NATO has strongly denied any plan for military action in Syria.