Syrian opposition fighters captured a military airport near the northern city of Aleppo yesterday in another military setback for President Bashar al-Assad’s forces which have come under intensifying attack across the country.

The airport is the latest military facility to fall under rebel control in a strategic region situated between Syria’s industrial and commercial centre and the country’s oil- and wheat- producing heartland to the east.

Fighting in the nearly two-year-old conflict has intensified in the three weeks since the political leadership of the opposition offered to negotiate a departure for Assad.

In the first direct government response, Syria’s minister for “national reconciliation”, Ali Haidar, said he was willing to travel abroad to meet Moaz Alkhatib, the Cairo-based president of the Syrian National Coalition opposition group.

Authorities had previously said they would talk to the “patriotic opposition” – figures who have not allied themselves with the armed rebellion. But most centrist opposition figures have left the country since Abdel-Aziz al-Khayyer, a proponent of dialogue and non-violence, was arrested last year.

“I am willing to meet Mr Khatib in any foreign city where I can go in order to discuss preparations for a national dialogue”, Haidar told the Guardian newspaper. But Haidar said the authorities rejected any dialogue that aims “to hand power from one side to another” and insisted that formal negotiation must take place on Syrian soil.

The main push for talks on a transition is coming from UN envoy Lakhdar Brahimi, a veteran diplomat who helped mediate an end to civil war in neighbouring Lebanon and warned that Syria could become a failed state. The Syrian uprising, in which 60,000 people have been killed, has been the bloodiest of the Arab revolts that already toppled four autocrats in Libya, Egypt, Tunis and Yemen.

With the minority Alawite sect, an offshoot of Shi’ite Islam, dominating power in Syria, the conflict has deepened the Shi’ite-Sunni divide in the Middle East.

In the capital Damascus, residents and activists said the army had moved tanks to central Abbasid Square to shore up its defensive lines after rebels breached it last week and then struck several security targets in the heart of the capital.

Jets bombarded rebel held areas in the east of the capital and in an expanse of farmland and urban areas known as Eastern Ghouta, from where rebels have launched an attack to cut off the loyalist supply lines.

Despite a large military arsenal – opposition activists reported several Scud missiles being fired at unknown targets from an army base north of Damascus – Assad’s forces appeared to be on the defensive in many parts of the country.

The army and a plethora of security forces remain entrenched in fortress-like bases in Damascus and the provincial capitals, where their advantages in air power and heavy weaponry have kept the opposition from taking over the major cities.