Syria crisis: Damascus blast 'kills 16 soldiers'
At least 16 Syrian soldiers have been killed in a suicide bombing and fighting that followed in a Damascus suburb, activists say.
The blast triggered clashes at a checkpoint near the mainly-Christian area of Jaramana, the Syrian Observatory for Human Rights said.
State media blamed "terrorists" for the explosion but did not give details.
Earlier, the US urged the Syrian government to allow aid to reach starving civilians in Damascus.
Washington said the army's months-long siege left many people in rebel-held areas in desperate need of food, water and medicine.
The UK-based Syrian Observatory for Human Rights, which relies on a network of activists inside Syria, said the suicide car bombing by the al-Qaeda-linked Nusra Front triggered heavy fighting at a key checkpoint between Jaramana and the rebel-held town of Mleha.
It said rebels fired rockets into Jaramana during the fighting and Syrian fighter jets retaliated by striking nearby opposition-held areas.
The report could not be confirmed.
The BBC's Jim Muir in neighbouring Lebanon says the use of suicide bombers to open an offensive is a tactic that has been used increasingly by the rebels in recent months.
Rebels control much of the countryside around Damascus but Jaramana - a Christian and Druze area mostly loyal to President Bashar al-Assad - is still held by the government.
In August a car bomb in the suburb killed 18 people.
Syria's embattled President Assad has drawn support from Syria's ethnic and religious minorities, including Christians and members of his Alawite sect, an offshoot of Shia Islam.
The rebel movement is dominated by Sunni Muslims, who are a majority in Syria.
In another development, British surgeon David Nott, who volunteered in a hospital in northern Syria for five weeks, has told the BBC he had treated pregnant women deliberately targeted by snipers.
"There was definitely a game going on between the snipers," he said.
"One day we would receive patients who had purely groin wounds, another day purely chest wounds or purely abdominal wounds. Then another day full-term pregnant ladies were coming in having been shot."
He added: "They were definitely targeted in the uterus. The majority of the babies didn't make it."
Mr Nott said he wanted the UK government to help open up a humanitarian corridor in Syria to allow aid and aid workers to enter the country safely.
In a statement on Friday, US State Department spokeswoman Jen Psaki called on the Syrian government "to immediately approve relief convoys".
She warned that "those who are responsible for atrocities in the Damascus suburbs and across Syria must be identified and held accountable".
At least three of Damascus's suburbs - Yarmouk, Eastern Ghouta and Moudamiyah - have been besieged by government forces for several months.
The situation has become so desperate that earlier this week Muslim clerics issued a religious ruling allowing people to eat cats, dogs and donkeys just to survive.
Those animals are usually considered unfit for human consumption in Islam.
More than 100,000 people have been killed in Syria's conflict, now in its third year. It began with popular protests against President Assad before degenerating into civil war.