Syria told the United Nations on Saturday that its belief in a military victory was "even greater" because the army was making "great strides" on the ground, with help from Russia, Iran and Lebanon's Hezbollah.
Syrian Foreign Minister Walid Muallem took the podium at the General Assembly as air strikes pounded Aleppo and diplomatic efforts to end the five-year war were deadlocked.
"Our belief in victory is even greater now that the Syrian Arab Army is making great strides in its war against terrorism, with the support of the true friends of the Syrian people, notably the Russian Federation, Iran and the Lebanese national resistance," Muallem said.
Intense air strikes toppled buildings and killed at least 45 civilians in Aleppo on Saturday while nearly two million people were without water in the war-battered city.
UN chief Ban Ki-moon said he was "appalled by the chilling military escalation" in Aleppo, which has come under heavy bombardment since the Syrian army launched a new offensive to retake the city two days ago.
Ban cited reports of air strikes involving the use of incendiary weapons, bunker buster bombs and other powerful munitions, warning that this could amount to war crimes.
In his address to the assembly, Muallem said his government was committed to the peace process, but he insisted that Damascus was involved in a life-or-death struggle against "terr orism".
"We, in Syria, are combating terrorism on behalf of the whole world," he said.
The foreign minister accused Western-backed opposition fighters of carrying out crimes that "are no less barbaric" than those attributed to Islamic State and Al-Qaeda jihadists.
Now in its sixth year with more than 300,000 dead, the war in Syria has dominated this year's annual gathering of world leaders at the United Nations.
Children are not terrorists
Muallem, who is also deputy prime minister, hit out at Qatar, Saudi Arabia and Turkey, accusing them of supporting armed "terrorists" with training and weaponry to fight President Bashar al-Assad's government. 1
Iraqi Foreign Minister Ibrahim al-Jaafari (R) meeting his Syrian counterpart Walid Muallem in the capital Baghdad (photo by: STRINGER/Iraqi Foreign Ministry/AFP/File)
The leader of Syria's opposition, Riad Hijab, told a news conference in New York a few hours after Muallem's address that the international community must change its approach to the Syrian conflict.
"The children of Syria are not terrorists. The people of Syria are not terrorists," said Hijab.
Hijab, the head of the opposition High Negotiations Committee (HNC), hit out at Russia for its support of the Damascus regime, saying it had lost credibility as co-chair with the United States of the Syria peace process.
"It is time for the international community to put a stop to this," he said.
Rebel-held districts in east Aleppo came under intense air and artillery fire for a fifth night as the army prepared a ground offensive to recapture the whole of the divided city.
Muallem also used his address at the General Assembly to reject US claims that a coalition strike on Syrian soldiers a week ago was unintentional, saying it was "not an error." 2
A Syrian boy awaits treatment at a make-shift hospital following air strikes on rebel-held eastern areas of Aleppo (photo by: Karam al-Masri/AFP)
Syria "holds the United States fully responsible" for the September 17 coalition strike on a Syrian army base "because facts show that it was an intentional attack, and not an error, even if the United States claims otherwise," he said.
Dozens of Syrian soldiers were killed in the bombing of the Syrian air base near the eastern city of Deir Ezzor, which is controlled by IS jihadists.
The United States has expressed regret for the loss of lives, saying the coalition believed it was hitting an IS target and promising to investigate the incident.
Syria reacted furiously to the strike, announcing the end of the truce on Monday. On that day, an aid convoy was hit by an airstrike that US officials have said was carried out by Russian planes.