Syrian rebels said on Wednesday that they would target the regime's intelligence apparatus in Aleppo, as President Bashar al-Assad hailed the "heroic" army in its battle against the opposition.
A UN official confirmed that the military had used fighter jets to fire on Syria's commercial capital, as clashes between troops and rebels also broke out near two Christian neighbourhoods of central Damascus, a watchdog said.
Buoyed by their capture of three Aleppo police stations in deadly clashes on Tuesday, the rebels said they were now turning their sights on the intelligence services in their battle for the key northern city which has raged since July 20.
"The most important thing is to take over the intelligence branches," said rebel commander Ferzat Abdel Nasser, an army general who defected a month ago. "If these sites fall, victory is possible."
Assad said the military was fighting a campaign that was vital to Syria's future.
"The army is engaged in a crucial and heroic battle... on which the destiny of the nation and its people rests," he said, in a speech carried by the official SANA news agency.
"The enemy is among us today, using agents to destabilise the country, the security of its citizens... and continues to exhaust our economic and scientific resources."
Assad's comments were echoed by Defence Minister General Fahd Freij, who vowed that the "terrorists" would soon be defeated.
"Seeing your heroic actions, I can assure the Syrian people that victory over this huge conspiracy is near," Freij said in a speech carried by SANA marking the 67th anniversary of the armed forces.
"The armed forces are determined to hunt down these groups wherever they are, to annihilate them and restore public security."
The Britain-based Syrian Observatory for Human Rights said members of a pro-government tribe had joined the fighting in Aleppo, following the execution of tribal leader Zeino al-Berri by rebels on Tuesday.
"Fierce clashes took place today between gunmen loyal to the regime, including the Al-Berri tribe and others, and rebel fighters in the neighbourhood of Bab al-Nayrab," said Observatory director Rami Abdel Rahman.
A security source in Damascus said the Al-Berri tribe had issued a statement promising to take revenge against the rebel Free Syrian Army.
The FSA's military chief in Aleppo, Colonel Abdel Jabbar al-Oqaidi, said the rebels had "thousands" of fighters in the city.
"The regime says it is fighting 'terrorist groups.' We tell the regime that we will chase them because they are the terrorists," Oqaidi told AFP.
"We will go after them in the whole of Aleppo, until the city is liberated."
The UN Supervision Mission in Syria said its observers had seen fighter jets used in Tuesday's fighting in the city of some 2,7 million people.
"Yesterday they saw firing from a fighter aircraft", said UNSMIS spokeswoman Sausan Ghosheh. "They are jets."
FSA spokesman Kassem Saadeddine said the rebels controlled half of Aleppo city and most of its province.
"We hope to create a safe zone in Aleppo and (northwestern) Idlib," on the border with Turkey, said .
A safe zone would enable rebels to bring in weapons more easily from nearby Turkey, and to set up a more organised military structure.
Oqaidi said: "The army's morale is at its lowest."
"They know that if they send in tanks next to houses and civilians, they risk higher defections. Soldiers are just waiting for their chance to defect."
The World Food Programme said it had sent food assistance for distribution to 28,000 people in Aleppo over the next few days.
"The humanitarian situation is deteriorating in Aleppo and food needs are growing rapidly," the UN agency said.
In Damascus, a firefight erupted on the outskirts Bab Tuma and Bab Sharqi, two traditional Christian districts of the capital that had previously been largely spared the bloodshed of the nearly 17-month uprising, the Britain-based Observatory said.
"First indications are that one soldier has been killed," it said.
Nationwide, at least 110 people were killed in violence on Wednesday -- 67 civilians, 29 soldiers and 14 rebels, the Observatory said.
On Tuesday, 124 people were killed nationwide, around half of them in Aleppo.
The Free Syrian Army hit out at the announcement by a civilian dissident group in Cairo on Tuesday that it intended to set up a government in exile.
"This government in exile was stillborn because it was made by a single group that does not represent the whole of the opposition," the FSA's spokesman inside Syria told AFP.
"Any project that marginalises groups in the country is a failure," Saadeddine said,
Veteran dissident Haytham al-Maleh, 81, told reporters on Tuesday that he had been tasked with forming a government-in exile, adding that he would consult "with the opposition inside and outside