DAMASCAS/GENEVA  - The Syrian regime accused regional powerhouses Saudi Arabia, Qatar and Turkey of trying to destroy the country and vowed Sunday that it would defeat rebels who have captured large swathes of the commercial hub Aleppo.

Military forces in Aleppo fired tank and artillery shells at neighbourhoods as rebels tried to repel the government air and ground assault. According to activists, rebels who launched an operation to take over Syria’s largest city a week ago are estimated to control between a third and a half of Aleppo’s neighbourhoods.

Foreign Minister Walid al-Moallem, on a visit to Iran, levelled some rare public criticism of powers in the Middle East, saying Qatar, Saudi Arabia and Turkey are supporting a plot hatched by Israel to destroy Syria. The three countries have all been backing rebels trying to overthrow authoritarian President Bashar Assad.

“Israel is the mastermind of all in this crisis,” Moallem told a joint news conference in Tehran with his Iranian counterpart Ali Akbar Salehi. “They (Qatar, Saudi Arabia and Turkey) are fighting in the same front.”

The battle for Aleppo, once a bastion of support for Assad’s regime, is critical for both the regime and the opposition. Its fall would be a major blow to Assad, giving the opposition a major strategic victory with a new stronghold in the north.

“They mobilized all their armed terrorists and tried to capture Damascus in less than a week,” Moallem said. “They were defeated. Today, they’ve gone to Aleppo and definitely they will be defeated in Aleppo,” he added. The rebels mounted a challenge to the regime in Damascus before the assault on Aleppo, but after a week of intense clashes, they were defeated.

Iran, Syria’s only remaining ally in the Middle East, has provided Assad’s government with military and political backing for years, and has kept up its strong support for the regime since the uprising began in March 2011.

Sunday’s bombardment was part of a government counter-offensive to retake control of districts that had fallen into rebel hands last week at the beginning of their bid to capture Aleppo.

Activists said the shelling was most intense in the southwestern neighbourhoods of Salaheddine, Bustan al-Qasr and parts of Saif al-Dawla, some of the first areas seized by the rebels when they started the push last week after being routed in a similar attack against the capital Damascus.

Syrian Interior Minister Mohammad al-Shaar vowed late Saturday that the Syrian army would root out terrorism and restore order to Syria. Al-Shaar was making his first televised appearance since he was wounded in the July 18 bomb attack in Damascus that killed four other top security leaders in Assad’s inner circle.

The Britain-based activist group Syrian Observatory for Human Rights also reported heavy fighting and explosions in Aleppo. It reported intense clashes in the Bab al-Hadeed, al-Zahraa and al-Arqoub neighbourhoods.

The international community has raised an outcry about a possible massacre in this city of 3 million but acknowledged there was little they could do to stop the bloodshed. The foreign minister of Russia, a powerful ally of Syria, said over the weekend it was “simply unrealistic” for Damascus to cede control of Aleppo.

Since the rebel assault on Aleppo began a week ago, about 162 people have been killed, mostly civilians, according to the Observatory. Some 19,000 people have been killed since the uprising began, the group says.

The violence has sent refugees flooding into neighboring countries including Jordan, Turkey, Iraq and Lebanon.

Jordan said it had opened its first tent camp for Syrians, saying a surge of refugees forced it to do so.

Authorities had been reluctant to set up the camps, possibly to avoid angering Assad’s regime by concentrating images of civilians fleeing his military onslaught.

But with 142,000 Syrians refugees and their numbers growing daily by up to 2,000, Foreign Minister Nasser Judeh said Sunday that Jordan had no other choice. He spoke at the camp’s opening ceremony in the hamlet of Zataari, about 11 kilometers (7 miles) from the northern border with Syria.

International envoy for Syria Kofi Annan has said he feared an “imminent battle” in Aleppo, the country’s economic capital largely held by rebels.

“I am concerned about reports of the concentration of troops and heavy weapons around Aleppo, in anticipation of an imminent battle in Syria’s largest city,” he said in a statement published in Geneva late Saturday.

Annan, the joint envoy for the United Nations and the Arab League, reiterated his call for parties to the conflict to work towards a political solution.

The Arab League chief described the situation in Syria as amounting to war crimes and said those responsible will be held accountable internationally, Egypt’s state news agency said on Sunday. “Dr Nabil Elaraby, Secretary-General of the Arab League, described what is happening in Syria, especially the city of Aleppo, as amounting to war crimes, and warned that perpetrators of these crimes will be held internationally accountable,” state news agency MENA said.