Syria conflict: Hopes fade for truce as violence flares
A week-old truce in Syria brokered by the US and Russia appears close to unravelling, with alleged violations by government and rebel forces mounting.
A US-backed rebel group in the divided northern city of Aleppo said the initiative had "practically failed".
The Syrian military said its seven-day "regime of calm" had expired and did not say if it would be renewed.
US Secretary of State John Kerry, however, described the cessation of hostilities as "holding but fragile".
He said US and Russian officials were meeting in Geneva on Monday to discuss developments.
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Witnesses reported air strikes and artillery fire hitting rebel-held parts of the city of Aleppo after the Syrian army statement.
The Syrian military said rebel groups, which it referred to as "terrorists", had failed to commit to any provisions of the deal.
The army said last week that its "regime of calm" would last until midnight on Sunday and then possibly be renewed. But the latest statement made no mention of a renewal.
Mr Kerry denounced the Syrian declaration, saying: "It would be good if they didn't talk first to the press but if they talked to the people who are actually negotiating this."
Earlier, Russia's defence ministry said rebel violations had made it "pointless" for Syrian forces to uphold the truce.
"Considering that the conditions of the ceasefire are not being respected by the rebels, we consider it pointless for the Syrian government forces to respect it unilaterally," Lt Gen Sergei Rudskoi said in a televised statement.
The BBC's James Longman in Beirut says there were never high hopes for the cessation of hostilities, but after just one week it looks to be in serious trouble.
"I believe that practically it has failed and has ended," Zakaria Malahifji, head of the political office of the Aleppo-based rebel group Fastaqim, told Reuters news agency.
Asked whether he expected aid to be delivered to the 250,000 people living in the city's besieged rebel-held east - a key part of the truce deal - Mr Malahifji said: "There is no hope. It has been a number of days of procrastination. Every day there is a pretext."
The UN's aid chief, Stephen O'Brien, said on Monday that he was "pained and disappointed" that a 20-lorry aid convoy destined for eastern Aleppo was still stuck on the border with Turkey because it had not received necessary permissions and safety guarantees from the Syrian government.
A number of leading rebel factions also warned that if the government pressed ahead with its plan to evacuate more rebel fighters from the besieged Homs suburb of al-Wair, it would "have clearly ended its commitment to any proposed truce".
A pro-government Lebanese TV channel reported that the rebels and their families had left on Monday, but a local official later told Reuters that the evacuation had been postponed until Tuesday.
The truce was dealt another blow on Saturday when warplanes from the US-led coalition against so-called Islamic State (IS) accidentally bombed Syrian troops in the eastern city of Deir al-Zour.
Officials said the strikes killed more than 60 soldiers. President Bashar al-Assad called them the "latest example of flagrant American aggression against Syrian army positions in the interests of the terrorist organisation Daesh [IS]".
On Monday, the UK confirmed that British aircraft - believed to be unmanned, remotely-piloted Reaper drones - had been involved in the strike, along with jets from Australia and Denmark.
A statement said the UK was "fully co-operating with the coalition investigation" and stressed that it "would not intentionally target Syrian military units".
Syria government warplanes meanwhile bombed rebel positions in Hama province, killing dozens of jihadist fighters, state media reported.
In another development, Turkish-backed Syrian rebel forces might extend their zone of control in northern Syria and seek to capture the IS stronghold of al-Bab, Turkish President Recep Tayyip Erdogan has said.
Mr Erdogan told a news conference in Istanbul that 900 sq km (350 sq miles) of IS territory had been cleared since last month, and that he envisaged the "safe zone" eventually extending up to 5,000 sq km.