AMMAN (Reuters) - Syrian rebels besieging a military airport near the border with Iraq were involved in serious fighting on Wednesday, opposition sources said, as rebels in the north of the country said they had shot down a fighter jet.
Free Syrian Army rebels have been laying siege to Hamadan airport in the city of Albu Kamal on the country's eastern frontier in Deir al-Zor province for the past three days.
Struggling to put down a 17-month-old uprising against his rule, President Bashar al-Assad has been increasingly relying on aircraft to attack the rebels, who are comparatively lightly armed with machineguns and rockets.
The opposition said the airport, where dozens of soldiers are still holding out, has been used by helicopters to launch bombing runs against rebel strongholds.
The rebels stepped up their attacks on air bases last week in an attempt to blunt Assad's air power which he has deployed to try to check rebel advances in urban and rural areas in the last month.
"The airport has effectively fallen after many soldiers defected," Nawaf al-Bashir, a senior tribal figure from Deir al-Zor who is in contact with rebels, said from Istanbul.
Abu Teif Ziad, another opposition campaigner from Deir al-Zor, said that the airport was the last base where government forces were present in Albu Kamal after rebels overran several army compounds in the town, which is situated on the Euphrates river a few kilometres from a crossing point with Iraq.
"If the Hamadan airport falls, Albu Kamal will come completely under rebel control," he said.
Attacks by rebels have already rendered two military airports in the northern province of Idlib - Taftanaz and Abu Thuhur - inoperational, according to an opposition source and diplomats.
REBELS SAY SHOT DOWN JET
Reports of heavy fighting outside the base came as rebels in the north of the country said they had shot down a fighter jet using a heavy machinegun.
Opposition fighters in Idlib province in the north-west of the country near Turkey said they had shot down the aircraft on Tuesday as it was taking off from the Abu Thuhur air base.
"They brought it down as it was taking off from the airport using 14.5 millimetre anti-aircraft machineguns," said Abu Majad, a spokesman from the rebel Ahrar al-Sham (Free Men of Syria) brigade.
It was impossible to verify the rebel statements as foreign media access to Syria is restricted. The rebels say they have shot down several fighter jets and helicopters in recent weeks.
If they seized Hamadan airport, a Western diplomat based in Amman said the rebels lacked the weapons to hold on to it, with sorties by Syrian fighter jets intensifying over the area.
"We have seen in the last few weeks the rebels making tactical advances by attacking the airports. They cannot hold on to them because the regime will simply send fighters jets and bomb them," the diplomat said.
As in most of Syria's 14 provinces, Assad's forces have concentrated their efforts on trying to prevent the provincial capital in Deir al-Zor from falling, while the rebels have been making advances in the countryside.
The revolt in Deir al-Zor has received a moral boost in the last two months with the defection of Nawaf al-Fares, Syria's ambassador to Iraq, and Prime Minister Riyad al-Hijab, two figures from the desert province where much of Syria's crude oil is produced.
Alliances between Sunni Muslim clans in Deir al-Zor and Assad's Alawite minority collapsed after Assad sent tanks into the city of Deir al-Zor to crush street protests against his rule last year.
(Reporting by Khaled Yacoub Oweis and Erika Solomon; Editing by Andrew Osborn)