(CNN) -- Syrian warplanes pounded volatile northern regions of the nation Tuesday, activists said.
Planes struck Maaret al-Numan and neighboring villages in Idlib province in the north, the opposition Local Coordination Committees of Syria said.
The town is strategically important to the government. It's on a main highway connecting Damascus and Aleppo, and the government needs it for moving reinforcements.
The LCC said at least 20 people died during "aerial shelling" in al-Mayadeen in Deir Ezzor province. They are among the 83 people slain across the country Tuesday, the group said.
Aerial shelling was reported in the Damascus suburb of Abada, and several people were wounded, the LCC said. It also occurred in the Raqqa province town of Ali Bajiliya amid clashes between rebels and government forces.
One person was killed and others were wounded in Hama by a bomb planted by regime forces, the LCC said.
More than 30,000 people have been killed in the country's 19-month-long conflict, regarded as a civil war.
Syrian state media said the nation's armed forces in Aleppo killed "terrorists" and destroyed vehicles, including one equipped with a missile launcher. It also said it killed "terrorists" in the Damascus countryside and other provinces.
In other developments:
U.N. agency slams attacks on health facilities
The World Health Organization has condemned violence against health services in Syria.
"The recent escalation of the conflict has resulted in substantial damage to health facilities across the country, limiting access and the provision of essential health services," the agency said Monday.
The group said almost 67% of public hospitals have been affected and 29% of those are out of service. It also cites damage to ambulances.
"Almost 271 out of 520 ambulances have been damaged or affected, of which 177 are out of service," the group said.
Turkey bulging with Syrian refugees
The number of Syrian refugees in Turkey now exceeds 100,000, a milestone underscoring the misery in war-ravaged Syria.
More than a dozen locations host about 100,363 Syrians, Turkish emergency management officials said Monday.
More than 143,000 Syrians have crossed the border into Turkey since April 2011 and more than 42,000 have returned to Syria, Turkey said.
By-elections in Syria
Syria will hold elections on December 1 to fill vacant parliamentary seats.
President Bashar al-Assad issued a decree setting the date, state media reported Tuesday.
Two of the seats are in Aleppo province, and one each will be up in Idlib, Hama and Hasaka provinces.
Turkey searches Syria-bound plane
For the second time in a week, Turkish officials Monday searched a civilian plane that had been headed to Syria.
Armenian and Turkish diplomats told CNN that an Armenian cargo plane that had been en route to Aleppo stopped first in the Turkish city of Erzurum on Monday morning for an inspection of its cargo.
The move appeared to be part of Turkey's enforcement of a newly adopted blockade against the Syrian government. After the search, which lasted at least five hours, the Armenian cargo plane was allowed to continue to Syria.
Special envoy to Syria makes visits
Seeking to forge a solution to Syria's bloody civil war, international envoy Lakhdar Brahimi visited the country's key ally in the region, Iran, before heading Monday to Iraq.
Brahimi met with Iranian President Mahmoud Ahmadinejad and called for an end to the flow of arms to both sides of the conflict, Brahimi's spokesman said.
Rebel fighters have accused Iran of sending advisers to help al-Assad put down the popular uprising.