A Hezbollah commander was killed in battle in Syria on Sunday, as a monitoring group accused regime forces of executing five civilians during fierce fighting near the Lebanon border.
The death of the Hezbollah commander came as Syrian President Bashar al-Assad's forces advanced in the key town of Nabuk, one of the last rebel-held areas of the strategic Qalamoun region along the Lebanese border.
A key member of the Syrian opposition meanwhile said the National Coalition would make a "final decision" later this month on whether to attend a Geneva peace conference planned for January 22 and aimed at ending the nearly three-year-old conflict.
Hezbollah, a Lebanese Shiite movement, has lost scores of fighters since it joined Assad in battling the Sunni-led rebels, inflaming sectarian tensions on both sides of the border.
A Lebanese security source confirmed that "Ali Bazzi, a high-ranking Hezbollah military commander, was killed today in a combat zone," without specifying the location.
A website for Bint Jbeil, Bazzi's hometown in southern Lebanon, also announced his death and posted pictures of him in military garb and holding an automatic rifle, saying he "died a martyr as he was carrying out his sacred duty as a jihadist."
Hezbollah chief Hassan Nasrallah has repeatedly defended his group's involvement in Syria, most recently on Tuesday in an interview with Lebanese broadcaster OTV.
Hours after that interview Hezbollah said a member of its secretive top leadership was shot dead near Beirut, blaming Israel for his murder.
Killings in Qalamoun
Hezbollah has been fighting alongside Syrian regime troops in Qalamoun in recent days, hoping to secure the mountainous area linking Damascus with the central Homs province and deprive the rebels of smuggling routes across the border to Lebanon.
"There is fierce fighting in Nabuk between government forces, backed by Lebanese Hezbollah fighters, and Al-Nusra Front and the Islamic State of Iraq and the Levant," two Al-Qaeda-linked groups, the Syrian Observatory for Human Rights said.
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The group, which relies on activists and medics on the ground for its information, said regime troops had "executed five civilians, including two children," in the town.
Activists said they were able to transport the bodies to Yabrud, a nearby area held by rebels, and they uploaded pictures on social media that they said showed the bloodied corpses of the two children, one of which had a head wound.
The Observatory said Assad's troops had taken "new sectors" of Nabuk Sunday after surrounding the town and pounding it with artillery for the past two weeks.
"The Syrian army is continuing to rake orchards in Nabuk, and has discovered a terrorist lair containing medical equipment and drugs," state television said, using the regime's term for the rebels.
At least 126,000 people have been killed in Syria since 2011, when protests begun in March of that year were met by a brutal crackdown that set off a full-scale civil war.
Opposition to make 'final' decision on talks
The United Nations plans to convene peace talks in Geneva next month to try to end the bloodshed, but the fractured Syrian opposition has yet to say whether it will attend.
The National Coalition, an external umbrella opposition group with increasingly tenuous ties to rebels on the ground, has said it will only attend the talks on the condition that Assad plays no role in the country's transition away from his family's four-decade rule.
But opposition member George Sabra told AFP Sunday that a "final decision" would be taken during a meeting of the Coalition in mid-December in Istanbul.
"I have doubts that the conference will take place," said Sabra, who heads the Syrian National Council (SNC), the largest member of the National Coalition.
The SNC has in the past said it would not attend the Geneva 2 talks.
"No one will dare go to Geneva without consulting with the forces on the ground who retain the real power," Sabra said.