'Foreign terrorists' fighting in Syria - Walid Muallem
Syria's foreign minister has claimed that "terrorists from more than 83 countries" are killing Syrian soldiers and civilians.
In a speech to the UN General Assembly, Walid Muallem compared this "invasion" to the 9/11 attacks on New York.
In a separate interview with the BBC, he said international peace talks were vital for Syria's future.
But he said proposed talks in Geneva "cannot succeed" while Turks, Saudis and Qataris are helping the rebels.
Meanwhile the UN has said the conflict in Syria is a threat to international stability.
Countries neighbouring Syria say the massive influx of refugees is putting a huge strain on their resources.
Speaking to the UN in New York, Walid Muallem accused "well-known" countries of backing "terrorists" fighting the Syrian government and of threatening "blatant military aggression outside the mandate of the Security Council".
He also dismissed the idea that there were moderate rebels in Syria, describing those fighting the Syrian government as terrorists.
"In Syria... there are murderers who dismember human bodies into pieces while still alive and send their limbs to their families," Mr Muallem said.
He said Syria had "repeatedly embraced" a political solution, but added that outside states - which he accused of supplying chemical weapons to Syrian rebels - had to abide by their commitments as well.
In a meeting at the sidelines of the conference, Mr Muallem told the BBC's Middle East editor Jeremy Bowen that a planned peace conference in Geneva "cannot succeed" unless regional countries like Turkey, Saudi Arabia and Qatar "refrain from supplying, arming, financing, smuggling" the rebels.
He did, however, reconfirm to the UN that Syria intended to co-operate with the Organisation for the Prohibition of Chemical Weapons (OPCW), which has been tasked with ensuring Syria's stockpile of chemical weapons is eliminated.
Syrian President Bashar al-Assad also confirmed he would comply with a plan to rid his country of chemical weapons, telling Italy's RAI News 24: "Of course we have to comply. This is our history. We have to comply with every treaty we sign."
On Friday, the UN Security Council passed a binding resolution to eliminate Syrian chemical weapons by mid-2014.
OPCW inspectors left for Syria on Monday to start implementing the plan.
A separate team of inspectors, from the UN, has been investigating allegations of chemical weapons attacks - both by government forces and rebel fighters.
These include an attack on 21 August in Damascus that left hundreds dead and triggered a threat of international military action against Mr Assad's forces.
Struggling to cope
The UN refugee agency UNHCR has been warning that the number of Syrian refugees from the conflict is threatening the political and social cohesion of the whole region.
UNHCR chief Antonio Guterres told the Geneva meeting that the "burden is far too heavy to be borne by only the neighbouring countries."
He said the international community should put in place more robust measures to share the cost of sheltering "an unrelenting flood of Syrian refugees".
Iraqi Foreign Minister Hoshyar Zebari said the arrival of more than 240,000 Syrian refugees since mid-September in Iraqi Kurdistan "had created a substantial burden on available resources and local economies".
The number of refugees might reach 350,000 by the end of 2013, he continued, and as winter approaches, "we require increased support from the international community".
Jordan's Foreign Minister, Nasser Judeh, said pressure on resources and public services were reaching "unbearable levels" and that the cost the Jordanians were paying as a result of this crisis was "unprecedented".
"The host communities' resilience has been undermined dramatically and public opinion is changing," he said.
Meanwhile, Turkish Foreign Minister Ahmet Davutoglu said the international community had "fallen short" in its response to the humanitarian crisis and "failed to provide an effective humanitarian response to put an end to this senseless violence".
Lebanon does not have the money, housing, schools or hospitals to cope, while Jordan and Turkey, with some 500,000 refugees each, are believed to have spent at least $2bn (£1.25bn) caring for them, the BBC's Imogen Foulkes reports from Geneva.
In an attempt to prevent Syria's neighbours closing their borders, traditional donors are being asked for financial support and offers to host some of the most vulnerable refugees, she says.
But the UN's $4.4bn appeal for Syrian refugees is only 50% funded, and there has been little response to appeals for Western states to resettle Syrians.
Britain and the US have not committed to accepting any so far, Germany will take 5,000, and Austria 500.
Unrest in Syria began in March 2011, developing into a conflict in which more than 100,000 people are estimated to have been killed.