* Urgent need for evacuations of wounded - Medecins sans Frontieres
* Deir al-Zor along urban battlegrounds in anti-Assad insurgency
BEIRUT, Dec 12 (Reuters) - Fighting has trapped tens of thousands of Syrians in the city of Deir al-Zor and there is urgent need for medical teams to be authorised to evacuate wounded people, Medecins Sans Frontieres (MSF) said on Wednesday.
The group, also known as Doctors Without Borders, said the Syrian government had yet to authorise the deployment of international aid agencies despite the growing humanitarian crisis in the major Arab country, but it would continue to try to raise its presence in Syria to help the wounded.
Deir al-Zor has become one of many urban battlegrounds in the 20-month-old revolt against President Bashar al-Assad in which more than 40,000 have died. With daily army shelling and routes cut off by fighting, many residents are trapped.
"MSF appeals for international and impartial medical assistance to be officially authorised by the government and for such assistance to be respected by all parties of the conflict," the group said in a statement.
Medical supplies are running short and only a small team of Syrian medics are left inside the embattled eastern city, MSF coordinator Patrick Wieland said, and six months of conflict in Deir al-Zor has left doctors exhausted.
Wieland, who visited the area, said there was now only one makeshift hospital with four doctors in city, which sits near the Iraqi border and was once home to around 600,000 people.
An MSF team unofficially visited Deir al-Zor province but said conditions were too dangerous for them to enter the main city with the same name. The team visited public and private hospitals around the city and said the premises were inundated with wounded, some of them with hundreds of patients.
"Despite support from a Syrian doctors' organisation, medical supplies are almost impossible to get hold of, and aerial bombardments and sniper fire make evacuating patients by stretcher extremely difficult," the MSF report said.
"The health system is being targeted, and medical supplies, including drugs and blood products, are running out, while the number of wounded continues to increase."
Other wounded patients, it said, were sent on a 400 km (250 mile) journey to Turkey, even though Deir al-Zor is very close to the Iraqi border, because Turkey has opened up its health care system to wounded Syrians.
"MSF calls for the evacuation of the wounded and sick from the city of Deir al-Zor to safer locations in respect of humanitarian law," the group said.
(Reporting by Erika Solomon; Editing by Mark Heinrich)