'At least 28 killed' in air strike on Syrian refugee camp
At least 28 people have been killed in an air strike on a refugee camp in north-western Syria, near the Turkish border, activists said.
The UK-based Syrian Observatory for Human Rights said the casualties include women and children.
The strike hit a camp for the internally displaced in the rebel-held territory near Sarmada, in Syria's Idlib province.
The Local Coordination Committees, another activist group, said more than 30 are dead.
The camp is home to hundreds of people who have fled from the surrounding Aleppo and Hama provinces.
Videos circulating on social media said to be from the camp show at least a dozen tents burned to the ground, charred bodies and injured women and children being loaded onto a pick-up truck.
The latest attack came just hours after a twin bombing in the central province of Homs killed at least 10 people and wounded scores, state media and regional governor Talal Barrazi said.
A car bomb first exploded in the main square of the village of Mukharam al-Fawkani, 28 miles east of the city of Homs, Syria's third largest.
As people gathered to help the victims, a suicide bomber riding a motorcycle detonated his explosives nearby. Four children and three women were among those killed, state TV said, and as many as 49 were wounded in the attack.
There was no immediate claim of responsibility but the Islamic State (IS) group has claimed to be behind several similar deadly attacks in Homs province.
The area of the blasts is close to where Syrian troops and IS gunmen have been fighting for control of the vital Shaer gas field, which fell to IS on Wednesday after the extremists overran 13 government checkpoints and captured a Syrian soldier.
The Observatory said 34 government troops and 16 militants have been killed in three days of fighting there.
Meanwhile, relative calm prevailed in the northern city of Aleppo amid a ceasefire announced on Wednesday by US officials in agreement with Russia. The Syrian military said the truce would only last 48 hours.
Syrian President Bashar Assad said in a letter to Russian President Vladimir Putin that Aleppo will eventually be victorious, comparing the Syrian government forces' resistance in the city to the protracted Second World War battle of Stalingrad.
In Aleppo, Syrian state media reported some violations of the truce, saying militants had fired more than 20 shells into government-held parts of the city, where 280 civilians have been killed over the past two weeks, according to the Observatory. The activist group said Thursday's shelling killed one person.
In his letter to Mr Putin, which was carried on Syrian state media, Mr Assad vowed that Aleppo and other Syrian cities and towns will defeat "the aggression" the way the Soviet Red Army defeated Nazi forces in Stalingrad.
"Aleppo today, as well as all Syrian cities embrace the heroic Stalingrad and pledge that despite the viciousness of the aggression... our cities, villages, people and army will not accept anything less than defeating the aggression," Mr Assad said.
It was unclear why Mr Assad was making the comparison, but the rhetoric could be playing to Russian patriotic sentiment ahead of Victory Day next week - May 9 marks the capitulation of Nazi Germany to the Soviet Union at the end of the Second World War.
Also on Thursday, renowned Russian conductor Valery Gergiev led the Mariinsky orchestra from St Petersburg in a concert at the ancient Syrian city of Palmyra, which was badly damaged by IS extremists who held the town for 10 months before Syrian troops captured it under the cover of Russian air strikes in March.
The concert, dubbed With A Prayer for Palmyra, was to support the restoration of the Unesco heritage site and in honour of the victims of Syria's war. It was held in the town's amphitheatre.
In opening remarks, Gergiev said that with the concert, "we protest against the barbarians who destroyed monuments of world culture".
There was also a video linkup in which Mr Putin addressed the audience, saying he regards the concert "as a sign of gratitude, remembrance and hope".
The White House said the air strike in north-western Syria was "indefensible".
Spokesman Josh Earnest said there is "no justifiable excuse" for an air strike targeting innocent civilians who have already left their homes to flee violence.
Mr Earnest said it was too early to say whether Mr Assad's forces had conducted the attack. But he said he believes no US or coalition aircraft were operating in the area.
Mr Earnest said if it turns out Mr Assad's government was responsible for using force against civilians, "it would not at all be the first time".