Rebels said they shot down a MiG warplane on Thursday as violence whipped across Syria ahead of a UN Security Council meeting to tackle deteriorating humanitarian conditions in the country and along its borders.
Egyptian President Mohamed Morsi meanwhile caused a storm with a speech at a Non-Aligned summit in Tehran, slamming the Syrian regime as "oppressive" and urging support for the opposition.
"I can confirm that a MiG (plane) was shot down this morning by our men using automatic weapons, shortly after taking off from Abu Zohur military airport in Idlib province," the rebel Free Syrian Army chief for the northern province, Colonel Afif Mahmoud Suleiman, told AFP.
"The two pilots who parachuted from the plane were captured," Suleiman said in claims that could not be immediately verified.
On August 13, rebels claimed the downing of a Russian-made MiG in the eastern province of Deir Ezzor, while on Monday rebels said they had shot down an army helicopter during fierce fighting in the Damascus suburb of Qaboon.
The Syrian regime acknowledged the first two aircraft crashes but put the causes down to mechanical failures. It has not immediately commented on the latest claim.
The Syrian Observatory for Human Rights had earlier said rebels took over parts of a military airport in Idlib overnight, and that sounds of explosions could be heard inside the facility.
The violence came as a war of words erupted between Egypt's Morsi and Syrian Foreign Minister Walid Muallem in full glare of NAM leaders soon after their summit began in the Iranian capital.
"The revolution in Egypt is the cornerstone for the Arab Spring, which started days after Tunisia and then it was followed by Libya and Yemen and now the revolution in Syria against its oppressive regime," Morsi said in his address to the gathering.
"Our solidarity with the struggle of Syrians against an oppressive regime that has lost its legitimacy is an ethical duty, and a political and strategic necessity," he added.
With his delegation walking out in protest, Muallem swiftly accused Morsi of using his speech to incite further bloodshed in Syria.
The speech amounted to "interference in Syria's internal affairs and ... incites continued bloodshed in Syria," he said, quoted from Tehran on Syrian state television.
On the sidelines of the summit, Morsi held talks with Iranian President Mahmoud Ahmadinejad on bilateral and regional issues including Syria, an official said.
"They emphasised the need to solve the Syria crisis via diplomacy and to prevent foreign intervention," Iranian Deputy Foreign Minister Hossein Amir Abdollahian told Iran's Arabic-language broadcaster Al-Alam.
The Security Council meeting has been called by France and is aimed at "appealing to world conscience and for mobilisation" in the face of the Syrian humanitarian drama, a diplomat said in New York.
Turkey has floated the idea of creating buffer zones within Syria to receive those displaced by the conflict so they do not flood across the borders into neighbouring countries.
Assad, however, scoffed at the idea in an interview Wednesday with pro-regime Addounia TV channel.
"Talk of buffer zones firstly is not on the table and secondly it is an unrealistic idea by hostile countries and the enemies of Syria," the embattled leader said.
French Foreign Minister Laurent Fabius, who will preside the UN meeting as France heads the Council in August, said Wednesday the issue of buffer zones would be brought up, even if "it is very complicated."
Syria's neighbours Jordan, Lebanon, Turkey and Iraq were all to send ministers to the meeting.
On the warfront, fierce clashes broke out near a military security headquarters in Deir Ezzor city, eastern Syria, while in the northern city of Aleppo, the contested districts of Salaheddin, Saif al-Dawla and Sukari were again the scene of fierce fighting, the Observatory said.
In the capital, gunfire reverberated Thursday across Qaboon, according to the Syrian Revolution General Council, a network of local activists.
Another activist network, the Local Coordination Committees, said that fighting also erupted in the capital's southern Tadamun district.
The Britain-based Observatory reported a total of 128 people -- 77 civilians, 19 rebels and 32 soldiers -- killed nationwide on Wednesday, including at least 44 civilians in Damascus.
In a preliminary figure, it said at least eight people had died on Thursday.
The director of the capital's Tishrin military hospital, meanwhile, said more than 8,000 members of the security forces have been killed since the uprising against Assad's rule broke out in March 2011.
"I estimate that at least 8,000 soldiers and members of the security forces have been killed since the beginning of the crisis," the director, a doctor who also holds the rank of general, told AFP, on condition of not being named.
"Every day, we receive an average of 15 to 20 bodies of soldiers and members of security forces, with the numbers increasing since the beginning of the year," he said.
The Observatory says that over 25,000 people have died in total in the 17-month-old uprising. It puts the figure of soldiers and members of the security forces killed at nearly 6,500.
Copyright AFP or Agence France-Presse, 2012 .