At least four people were killed Friday in mortar fire near the famed Ummayad mosque in Damascus, as Syrian forces pressed an operation against rebels in the strategic Qalamoun region.
Government forces bombarded one of two remaining rebel holdouts Qalamoun, northwest of the capital, as Prime Minister Wael al-Halqi flew to Iran for talks with the key regime ally.
In Geneva, meanwhile, the UN released a new report highlighting the plight of Syrian child refugees.
"Mortars fired by terrorists in front of the Ummayad mosque have killed four people and injured 26," state television said, using the regime term for rebels.
Central Damascus is regularly targeted by rebels from rear bases on the outskirts of the capital.
On Thursday, a Syrian was killed and nine others wounded when mortar fire hit the Russian embassy, the foreign ministry in Moscow said.
Outside of Damascus, the army pressed its campaign to encircle rebels near the capital by capturing Qalamoun and severing rebel supply lines across the border with Lebanon.
The army has already captured the towns of Qara and Deir Attiyah on the Damascus-Homs highway, and is pressing south towards the capital.
On Thursday, it entered the town of Nabuk, home to some 55,000 people, including a Christian minority, which lies 80 kilometres (50 miles) north of Damascus.
And on Friday, the Syrian Observatory for Human Rights said troops were heavily bombarding rebel positions that had prevented them from advancing further into Nabuk.
The army has "apparently decided to use overwhelming force," Observatory director Rami Abdel Rahman said.
A Syrian security source said the army had only Nabuk, nearby Yabroud and a handful of surrounding villages left to capture before completely securing the Qalamoun region.
"If this town is captured, all we'll have left is Yabroud and some other villages to completely block off the border with Lebanon and to stop any entrance or exit of rebels into Lebanon," the source said.
"The next phase will be to retake the south (of Syria). The north and the east are for later," he added, referring to areas under the control of the rebels or of Kurdish militia.
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Qalamoun has been a key rear-base for the rebels, who have used the mountainous region to store arms and as a transit point for fighters.
The army's operations there, as well as against the rebel stronghold of Eastern Ghouta outside the capital, have been bolstered by outside support.
Both Lebanon's Shiite group Hezbollah and the Iraqi Shiite Abul Fadl al-Abbas Brigade are fighting alongside the regime.
According to the Observatory, Hezbollah has lost some 17 fighters and the Abbas Brigade another 11 in the operations in the past two weeks.
A pro-Hezbollah site published the photos of 11 "martyrs."
A source close to Hezbollah said Thursday that a nephew of Lebanese Agriculture Minister Hussein Hajj Hassan, a prominent Hezbollah figure, was killed a day earlier along with three comrades.
The operation comes as the international community pushes the regime and opposition to attend peace talks in Geneva on January 22.
The regime has said it will attend the talks, but insists that President Bashar al-Assad's departure from office will not be on the table.
The key Syrian opposition National Coalition has welcomed the setting of the date as "very positive" but insists Assad can have no role in Syria's future.
It also wants to see humanitarian aid delivered to Syria, the release of prisoners and "an immediate end" to massacres before the talks begin.
In Geneva on Friday, the UN warned that Syria's children were among the worst-affected by their country's conflict.
In a special report, the UN High Commissioner for Refugees said children make up around half of the 2.2 million Syrian refugees.
"It is important that this human face of the refugee crisis is not forgotten," Volker Turk, UNHCR head of international protection, told journalists in Geneva.
"And if you look at what children face, they illustrate very strongly what this crisis is all about."