UN peace envoy for Syria Staffan de Mistura on Thursday vowed to press on with efforts for a truce in Aleppo, adding that wanted a resolution of the devastating conflict this year.
De Mistura, a Swedish-Italian diplomat appointed as UN envoy on Syria in July, said the second city of Aleppo was a "symbolic microcosm of all of Syria".
This was so "because it has the highest number of displaced people, because it has seen two years of suffering, because while the government and the opposition continue being involved in heavy fighting between them, ISIS is only 20 miles away from Aleppo", he said, referring to the Islamic State group.
"I am just determined to raise the fact that Aleppo cannot be abandoned," he said.
"We are engaged in intense discussions with the government... and the opposition regarding the freeze," he said.
De Mistura said the international community had to make sure that the Syrian conflict did not go in a "backburner," adding: "Movement towards some kind of political solution should take place this year."
"We need to make sure that this does not become like 2014 when we heard similar appeals from all of us, including the UN, and nothing really happened."
De Mistura said the Syrian conflict had rendered 12 million people in need, 7.6 million displaced, 3.3 million refugees and claimed 220,000 lives.
The ancient city of Aleppo has been fought over mercilessly since a popular uprising against President Bashar al-Assad began in 2011.
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Damascus wants the rebels to hand over their heavy weapons and allow the return of local administration officials to Aleppo.
The rebels in turn want a guarantee that the freeze will be total and not simply allow Damascus to redeploy its troops elsewhere.
De Mistura said he was pinning his hopes on planned Syria peace talks due later this month in Moscow.
"We are hoping ...that it will be a success in the sense that there will be an opportunity for a genuine dialogue between Syrian representatives but also Syrian authorities," he said.
He said he did not forsee a third round of Syria talks in Switzerland currently as the conditions were not right. Two rounds were held in the Swiss cities of Montreux and Geneva early last year but ended in a stalemate.
Assad meanwhile on Thursday said hoped-for talks in Moscow with opponents must focus on the fight against "terrorism" and voiced pessimism about their outcome.
"We are going to Russia not to start a dialogue, but to meet with these (opposition) figures and to discuss with them the framework of a dialogue," Assad said in an interview with Czech newspaper Literani Noviny.
However it is uncertain how the talks can take place, because the exiled opposition has already announced it will not attend.
Damascus-tolerated movements have mostly either rejected Moscow's invitation or have yet to decide whether they will attend.