French President Francois Hollande on Wednesday joined calls for international observers to oversee the evacuation of civilians trapped under fire in the wrecked Syrian city of Aleppo.

Turkey on Wednesday accused the regime in Damascus and its supporters of hampering the implementation of a ceasefire deal that would allow civilians and fighters to leave Aleppo -- Syria's second city.

"We now see that the (Syrian) regime and some separate groups are trying to prevent this (agreement)," Turkish Foreign Minister Mevlut Cavusoglu told reporters in Ankara. "The evacuation could not take place in the full sense."

Syria's rebels once dreamed of overthrowing President Bashar al-Assad's government and taking control of the country, but with the imminent loss of Aleppo they now face the prospect of total defeat.

Though rebels retain territory elsewhere in Syria, including almost all of neighbouring Idlib province, a crushing defeat in the country's second city would be highly symbolic.

Shelling and air strikes sent terrified residents running through the streets of Aleppo on Wednesday as diplomats strove to save a deal to evacuate rebel-held districts of the city.

When it was ruled by jihadists, residents of Qayyarah in northern Iraq had to travel for hours through checkpoints if they needed medical treatment.

But this week, Mahmud drove his son Mohammed straight to a new emergency unit in town after a mine exploded in the young boy's hand while he was playing.

The Islamic State group claimed responsibility for a bomb attack on a Cairo church that killed 25 people, in a statement circulated on social media on Tuesday.

The United States on Tuesday called for international observers to be allowed in Aleppo to oversee the evacuation of civilians following reports that Syrian forces had executed people during house-to-house searches.

U.S. Ambassador Samantha Power told an emergency Security Council meeting that the observers would "oversee the safe evacuation of the people who wish to leave but who, justifiably fear that if they try, they will be shot in the street or carted off to one of (Syrian President Bashar) Assad's gulags."

A coalition drone strike in Syria killed three Islamic State group leaders involved in plotting foreign attacks, including two men who helped facilitate last year's attacks in Paris, the Pentagon said Tuesday.

"The three were working together to plot and facilitate attacks against Western targets at the time of the strike," Pentagon press secretary Peter Cook said in a statement.

Press freedom groups called Tuesday for safe passage for media workers trapped inside a small remaining pocket of rebel territory in Syria's east Aleppo as the army advances.

Four suspects in a Cairo church bombing which killed 25 people have been referred to state security prosecutors for a remand hearing, officials said on Tuesday.