At least 16 fighters, including a high-ranking official from the the al-Qaeda-linked al-Nusra Front were killed Thursday in air raids on Syria's north-western Idlib province, a monitoring group said.
The raids targeted Abu Zohour military airport at the outskirts of Idlib, which is manned by al-Nusra, and their allies, the Islamic Turkistan Party, the Britain-based Syrian Observatory for Human Rights said.
The watchdog did not say if the planes were Russian or from the US-led coalition.
Al-Nusra took control of Abu Zohour military airport in September 2015.
Earlier, Islamist rebels led by al-Nusra Front, seized a key village loyal to Syrian President Bashar al-Assad and kidnapped dozens of people, the Observatory reported.
It said the rebels took control of al-Zara village on the southern outskirts of the central province of Hama following clashes with regime forces.
Observatory head Rami Abdel-Rahman told dpa that the rebels had seized dozens of civilians and pro-regime militiamen whose fate was still unknown.
Regime warplanes have targeted al-Zara with at least 40 airstrikes since the rebels captured it, the watchdog said.
The rebels' attack on the village was reportedly codenamed "Revenge for Aleppo," a reference to the northern city that has been a key battleground between al-Assad's forces and opposition rebels in recent weeks.
The regime and rebels were launching retaliatory attacks in Aleppo, hours after a temporary ceasefire ended in the city, activists said. Once Syria's commercial hub, Aleppo is now divided between the government-held west and the rebel-controlled east.
Regime warplanes bombarded the rebel-held districts of al-Zahara and al-Maysar shortly after the truce ended at midnight Wednesday, the Observatory said.
Rebels retaliated by firing at least three shells at dawn on Aleppo's regime-controlled neighbourhood of Seif al-Dawla, the watchdog added.
Mahmoud al-Shami, an activist based in the rebel-held side of Aleppo said that regime jets carried out air raids in the area following the end of the truce.
On Monday, the Syrian army said it had extended a 72-hour truce in Aleppo and its countryside for a further two days.
Retaliatory shelling and government airstrikes have claimed almost 300 civilian lives in Aleppo since April 22, according to the Britain-based Observatory that relies on a network of activists inside Syria.
Several Syrian areas have been besieged by government forces and rebels during the conflict that started with peaceful pro-democracy protests in March 2011.
Meanwhile, the first humanitarian aid in nearly four years to be delivered to Daraya, a Damascus suburb besieged by government forces, was turned back at the last government checkpoint, the UN and its parter organizations said.
"Daraya has been the site of relentless fighting for more than three and a half years, and we know the situation there is desperate," said Yacoub El Hillo, UN resident and humanitarian coordinator in Syria.
Stephane Dujarric, a spokesman for UN Secretary General Ban Ki-moon, had initially said that the UN and its aid partners aborted the mission because food items meant for children had been removed at the checkpoint, but later clarified that the convoy was refused entry because of the medical and food supplies on board.
The convoy had been previously granted clearance to go into Daraya.
The convoy was supposed to provide essential medical supplies, including vaccinations; nutrition items for children; hygiene items and school kits.
Fadi, an activist based inside Daraya, said shortly after the joint aid convoy was turned away, the regime shelled Daraya with mortars, killing a man and his son, who were waiting for the convoy to enter Daraya.
Daraya is located some 8 kilometres south-west of the centre of Damascus.
Its pre-war population was estimated at nearly 79,000 people. The town's population at present ranges between 4,000 and 8,000, according to the UN estimates.