BEIRUT: With attention focused on military operations on the Turkish border Thursday, violence continued unabated across Syria as rebels and government forces battled for control of key urban centers.

Regime forces battered Aleppo with a fierce shelling campaign, a day after a string of rebel bombings ripped through the northern city, killing at least 48 people.

Near the capital Damascus, forces loyal to President Bashar Assad also suffered a setback when rebels killed 21 members of the elite Republican Guard in the Qudsaya province, the opposition Syrian Observatory for Human Rights reported.

The Observatory said the toll of Republican Guard killed in Qudsaya, west of Damascus, may rise given the ferocity of the violence.

“The rebels likely used a small explosive device, but it was placed near the Republican Guard’s living quarters in Qudsaya,” said Observatory director Rami Abdel-Rahman, adding that clashes persisted after the blast.

The attack occurred a day after the army launched a major offensive on Qudsaya, the Britain-based Observatory and AFP journalists said, and activists reported regime forces carried out a large number of arrests in the area.

In Aleppo, an activist calling himself Abo Hamdo said intense tank shelling and aerial bombardment had started in the early morning in the Shaar, Tariq al-Bab, Al-Myassar, Bustan, Al-Basha and Al-Sakhour neighborhoods.

“The shelling is non-stop and then we have aerial bombardment three to four times a day,” he said.

Wednesday, a string of explosions in the heart of Aleppo killed at least 48 people in attacks claimed by the shadowy Islamist group Al-Nusra Front.

Government and rebel forces have been locked in a bloody stalemate for control of the strategic commercial center for over six weeks now. Rebels have launched what they called a “decisive battle” in the city, while the army has pledged to clear the city of opposition forces, but so far neither side has managed to gain the upper hand.

Abo Hamdo said it was impossible to gauge which side was advancing day by day, in a battle that city residents are growing increasingly weary of.

“No one has an exact idea ... both sides still fight every day,” he said via Skype. “The FSA every day [gains] new areas, and then the next day the government take these areas back. So nothing happens.

“The civilians are now just searching for an end.”

Elsewhere across the country, another five soldiers were killed and 16 wounded in an attack by rebels in the Quneitra province, bordering the Israeli-occupied Golan Heights, the Observatory reported.

Meanwhile in Zabadani, northwest of Damascus, the army and rebels clashed, said the Observatory.

“The quality of operations staged by the rebels is improving,” said Abdel-Rahman. “This is especially noticeable in Damascus province, which is strategic for both the rebels and the regime because of its proximity to the capital.”

But in the outer eastern suburbs of Damascus, activists said fighter jets were bombarding neighborhoods with TNT, or barrel bombs.

Syria’s military also turned its artillery on the provinces of Deir al-Zor in the northeast, Homs in central Syria and Idlib in the far northwest, said the Observatory.

At least 97 people were killed across Syria Thursday – 40 soldiers, 36 civilians and 21 rebels, according to an updated Observatory toll. The opposition group Thursday put Wednesday’s death toll at 236.

More than 31,000 people have been killed since the outbreak in March last year of an anti-regime revolt, which began as peaceful protests for reform but morphed into an armed insurgency when demonstrations were brutally crushed.