Syria's army on Tuesday turned its sights to the town of Yabrud, the last rebel stronghold in the strategic Qalamoun region near Lebanon's border, after a string of battlefield victories.
The town is believed to be where a group of nuns from the historic Christian hamlet of Maalula have been transferred, reportedly in the hands of jihadist rebels from Al-Nusra Front.
In Spain, meanwhile, El Mundo newspaper announced that two Spanish journalists, Javier Espinosa and Ricardo Garcia Vilanova, have gone missing in northern Syria.
The pair are believed to have been kidnapped in September by the Islamic State of Iraq and the Levant (ISIL), a jihadist group linked to Al-Qaeda.
The United Nations said it would for the first time begin airlifting aid into parts of northern and northeastern Syria from across the border in Iraq.
And the international chemical weapons watchdog announced that the destruction of Syria's chemical weapons could begin in late January.
In Qalamoun, the Syrian Observatory for Human Rights monitoring group said regime forces were shelling Yabrud, a day after they captured the town of Nabak.
Regime forces had "pounded the outskirts of Yabrud and the Rima area and the outskirts of the town of Nabak," it said in an email.
Government forces, reportedly backed by fighters from Lebanon's Hezbollah movement and members of a pro-regime militia, have seized Nabak, Deir Attiya and Qara.
The town lies along the strategic Damascus-Homs highway, which is expected to reopen soon after being closed by the fighting.
The regime advance along the highway allowed rebel fighters to re-enter Maalula last week, shortly after which a group of nuns from the Mar Takla convent were reported kidnapped.
Religious officials, including the Vatican's envoy to Damascus and the mother superior of a nearby convent, have said the 12 nuns are in Yabrud.
The women appeared Friday in a video broadcast by the Al-Jazeera news channel, apparently in good health and denying they had been kidnapped.
It was unclear who was filming the video, and whether the nuns were speaking under duress.
They were dressed in their traditional black robes and head coverings, but none were wearing their usual crucifixes.
In Spain, El Mundo said journalists Espinosa and Vilanova had been kidnapped on September 16 in Raqa province.
Despite indirect contact with the kidnappers, which resulted in information last month suggesting the pair are still alive, there has been no progress towards their release, nor any demands made.
Espinosa's wife, speaking at a news conference in Beirut, noted the journalists had braved fierce conflict to report on the plight of Syrians.
"Javier and Ricardo are not your enemy. Please, honour the revolution they protected, and set them free," she said.
The Syrian opposition Local Coordination Committees also said Tuesday that four prominent activists, including Razan Zeitouneh, had been kidnapped by members of the armed opposition.
In Geneva, meanwhile, the UN said it would begin sending 40 metric tonnes of aid from Iraq into Syria on Thursday.
"Our colleagues on the Iraqi side, with the permission of the Syrian government and also the cooperation of the Iraqi government, (are preparing for the) airlifting of supplies for winter from Arbil in Iraqi Kurdistan to Qamishli and Hasakeh in north and northeast Syria," Amin Awad, who heads the UN refugee agency (UNHCR) Syria response, told reporters in Geneva.
"UNHCR has operated an airlift from Damascus to Qamishli from July," but "this is to my knowledge the first international airlift," UNHCR spokesman Peter Kessler told AFP by phone.
The United Nations had originally planned to bring in the aid by road.
"But there was a shift in the elements that controlled that road and the border and we shifted to an airlift," Awad said.
The Organisation for the Prohibition of Chemical Weapons, which received its Nobel Peace Prize Tuesday, said destruction of Syrian chemical weapons aboard a US ship could start next month.
"We hope that by the end of January, the destruction on the American ship could start," director general Ahmet Uzumcu told AFP.
But he warned the timeline depended on security in Syria, adding "unfortunately the security situation has deteriorated over the past weeks".