Five civilians were killed in heavy fighting around a Palestinian refugee camp in the Syrian capital on Tuesday as rebels withdrew from a northwestern town after a night of clashes, a watchdog said.
Meanwhile, Information Minister Omran al-Zohbi renewed a call for opposition figures to enter into a dialogue for peace offered by President Bashar al-Assad, despite domestic and rebel groups already rejecting the proposal.
Four of the civilians were killed in shelling and the fifth by a sniper as battles raged between troops and rebels near the Yarmuk refugee camp in southern Damascus, the Syrian Observatory for Human Rights said.
In Idlib province in the northwest, the army drove rebels out of Mastuma, just south of the provincial capital, with the support of a "special operations battalion," a military source told AFP.
Displaced residents said troops stormed the town during the night, clashing with rebels and executing a number of residents.
They said snipers were deployed throughout the town and troops stationed in the nearby ruling Baath party camp, which the Britain-based Observatory said was turned into a military detention centre in summer 2011.
The camp is a strategic target because it contains the largest concentration of tanks in the area and sizeable stores of weapons and ammunition, Observatory director Rami Abdel Rahman said.
Also in Idlib province, rebels shot down a helicopter as it was headed towards the Taftanaz military airbase, which remains under siege by the jihadist Al-Nusra Front and Islamist Ahrar al-Sham groups, the Observatory said.
Troops still have a stranglehold on Idlib city but most of the province, which borders key opposition backer Turkey, is in the hands of insurgents.
In eastern Syria, a civilian cargo plane was hit while landing at Deir Ezzor military airport as clashes raged nearby, the Observatory said.
Activists said they suspected it was carrying munitions for beleaguered troops defending the base.
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The rebels now control large swathes of northern and eastern Syria and half of second city Aleppo, with the remaining isolated army outposts under rebel siege.
In other developments in the area, the Observatory said fighters from the Al-Nusra Front executed three captured soldiers in Deir Ezzor city, although it could not say when.
Overall, the Observatory said 58 people died nationwide on Tuesday.
The United Nations estimates more than 60,000 people have been killed since the revolt against Assad's rule erupted in March 2011.
On the political front, Information Minister Zohbi said the invitation for talks had been issued "to all opposition forces to join a dialogue based on respect for national sovereignty and a rejection of foreign intervention of all kinds," state news agency SANA reported.
But he qualified that by saying the government would be contacting "all political forces and personalities that are patriotic" to take part.
The comments repeated an offer made by Assad on Sunday to hold discussions with Syria's opposition to end the conflict -- but only with elements he deemed acceptable, not rebel-affiliated groups he termed killers and terrorists led by foreigners.
The main, internationally recognised opposition Syrian National Coalition, based out of Cairo, immediately dismissed Assad's offer, sticking to its pre-condition that the president step down before any talks could be considered.
And the tolerated domestic opposition group, the National Coordination Body for Democratic Change in Syria, also snubbed the offer.
Western nations described as essentially empty and detached from reality Assad's speech outlining a plan to restore peace to Syria while defiantly making no compromises.
In other developments, Britain will host a two-day meeting starting on Wednesday, officials said, bringing together academics and the opposition to prepare for a hypothetical post-Assad Syria.
"The UK's objective is to galvanise international thinking and planning on a Syrian-led political transition," a foreign office spokesman said.