Syria’s army resumed shelling the last rebel-held parts of Aleppo on Wednesday, a monitor said, ending hours of calm after a deal to evacuate civilians and rebels was announced.

“This morning, regime forces fired at least 14 shells onto the area held by the rebels for the first time since Tuesday,” said Rami Abdel Rahman, director of the Syrian Observatory for Human Rights.

“Mortar fire was also heard on the front line between rebel- and regime-held areas,” he said.

An AFP journalist in government-controlled west Aleppo heard the bombardment.

This photo released by the Syrian official news agency SANA, shows Syrian troops and pro-government gunmen marching walk inside the destroyed Grand Umayyad mosque in the old city of Aleppo, Syria, Tuesday, Dec. 13, 2016. (SANA via AP)

This photo released by the Syrian official news agency SANA, shows Syrian troops and pro-government gunmen marching walk inside the destroyed Grand Umayyad mosque in the old city of Aleppo, Syria, Tuesday, Dec. 13, 2016. (SANA via AP)

The renewed fighting came as the evacuation of thousands of civilians and rebel fighters from east Aleppo failed to begin as scheduled at dawn.

A deal to evacuate civilians and rebels from opposition-held parts of Aleppo was meanwhile put on hold after objections from Syria’s government, rebels and a source close to the regime said Wednesday.

Syrian residents, fleeing violence in the restive Bustan al-Qasr neighborhood, arrive in Aleppo's Fardos neighborhood on December 13, 2016, after regime troops retook the area from rebel fighters. (AFP PHOTO / STRINGER)

Syrian residents, fleeing violence in the restive Bustan al-Qasr neighborhood, arrive in Aleppo’s Fardos neighborhood on December 13, 2016, after regime troops retook the area from rebel fighters. (AFP PHOTO / STRINGER)

Rebels said the government and its ally Iran were blocking the deal’s implementation.

The source close to the regime said the government was objecting to the number of people that would be evacuated and demanding their names.

Thousands of cold and hungry civilians crowded the streets of Aleppo uncertain of their future.

Some had slept in the open, despite the cold and a fierce storm that brought heavy rain and high winds, after fleeing from other districts as they army advanced and finding nowhere to shelter.

This photo released by the Syrian official news agency SANA, shows Syrian troops and pro-government gunmen marching through the streets of east Aleppo, Syria, Tuesday, Dec. 13, 2016. (SANA via AP)

This photo released by the Syrian official news agency SANA, shows Syrian troops and pro-government gunmen marching through the streets of east Aleppo, Syria, Tuesday, Dec. 13, 2016. (SANA via AP)

The first departures had been expected to begin around 5:00 am (0300 GMT), but hours later there was no sign of movement.

Buses wait to evacuate civilians from eastern Aleppo, December 14, 2016. / AFP PHOTO / George OURFALIAN

Buses wait to evacuate civilians from eastern Aleppo, December 14, 2016. (AFP PHOTO / George OURFALIAN)

Drivers were sleeping inside the two dozen green government buses, which arrived late on Tuesday soon after the deal was announced.

No aid has entered east Aleppo since mid-July, when government troops first encircled rebel districts of the city, and food supplies have dwindled, forcing many to survive on as little as a meal every two days.

The army has seized virtually all of east Aleppo, in rebel hands since 2012, since beginning an operation to recapture the city last month.

Losing their onetime bastion will deal the opposition its worst blow since the conflict began in March 2011 and mark a major victory for President Bashar Assad and his allies Iran and Russia.

Turkey said those leaving would be taken to Idlib, which is controlled by a powerful rebel alliance that includes Al-Qaeda’s former affiliate Fateh al-Sham Front.

Turkish Deputy Prime Minister Mehmet Simsek (screen capture: YouTube)

Turkish Deputy Prime Minister Mehmet Simsek (screen capture: YouTube)

Deputy Prime Minister Mehmet Simsek said Turkey would “set up a tent city to accommodate up to 80,000 Syrian refugees fleeing Aleppo”.

US ambassador to the United Nations Samantha Power urged international supervision of the evacuation, expressing concern about “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 Assad’s gulags.”

While tens of thousands of civilians have already fled east Aleppo for government-held territory, others say they fear arrest or torture at the hands of the regime.