Hundreds of fighters from Iran-backed Iraqi militias crossed into Syria overnight to help the government fight rebels who seized Aleppo last week, Syrian and Iraqi sources said on Monday, and Tehran pledged to aid the Damascus government.

Iran's constellation of allied regional militia groups has long been integral to the success of pro-government forces in subduing rebels who rose up against President Bashar al-Assad in 2011, and they have long maintained bases in Syria. At least 300 fighters crossed late on Sunday using a dirt road to avoid the official border crossing, two Iraqi security sources said.

Iranian Foreign Minister Abbas Araqchi, who visited Damascus, said on Monday Syria's military was capable of confronting the rebels but, referring to the regional militia groups Tehran backs, he added that "resistance groups will help and Iran will provide any support needed."

Syrian government and Russian warplanes intensified attacks on Monday in areas held by rebels in the northwest, residents and rescue workers said, including a strike on a displaced people's camp that killed seven.

The Syrian government said Syrian and Russian air forces were striking rebel-held positions in the countryside east of Aleppo city.

The White Helmets rescue organization and residents of rebel-held areas in the north said warplanes had hit residential areas of Aleppo city and a displaced people's camp in Idlib province where seven people were killed, including five children.

The government said the military was working to secure towns it recaptured from rebels on Sunday that run along the front line north of Hama, a city lying between Aleppo and the capital Damascus.

Rebels seek political dialogue

The lightning rebel assault last week caught many in the region unaware, dealing Assad his biggest blow in years and reigniting a conflict that had appeared frozen for years after civil war front lines stabilized in 2020.

Although Russia has been focused on the war in Ukraine since 2022, it retains an airbase in northern Syria. The main Iran-backed group, Lebanon's Hezbollah, has been focused on its own war with Israel since the Gaza conflict began last year.

WATCH | Airstrike hits Aleppo hospital: 

Inside an Aleppo hospital after a deadly Russian military airstrike

A Russian airstrike at the Aleppo University Hospital in Syria killed at least 12 people and injured more than 20 others. The bombardment, in support of Syrian government forces, followed insurgents seizing control of Aleppo, the country's largest city.

Syria's conflict erupted in a rebellion against Assad's rule in 2011 and the rebels held much of Aleppo from 2012 until 2016, when government forces retook it with help from Russia and Iran-backed militia in a major turning point of the war. Any prolonged escalation in Syria risks further destabilizing a region already roiled by the conflicts in Gaza and Lebanon, with millions of Syrians already displaced and with regional and global powers backing rival forces in the country.

The rebels include mainstream groups backed by Turkey, as well as the Islamist Hayat Tahrir al-Sham, which was formerly affiliated with al-Qaeda. Turkey also has a military presence in a strip of Syrian territory along its border.

Kurdish-led forces that Ankara calls terrorists, but which fought Islamic State militants with U.S. help, hold territory in the northeast.

The Turkish and Iranian foreign ministers met on Monday and discussed the fighting in Syria. Turkish Foreign Minister Hakan Fidan said rebel advances could not be explained by foreign intervention and urged the Syrian opposition to compromise.

Russia, whose 2015 entry into the conflict turned the military balance decisively in Assad's favour continues to support the Syrian president and is analyzing the situation on the ground, Kremlin spokesperson Dmitry Peskov said. On Sunday, Moscow dismissed the general in charge of its forces in Syria, Russian war bloggers reported.

In Turkey, Syrian opposition leader Hadi al-Bahra said the rebels sought to force the Syrian government to accept a political transition.

"We are ready to start negotiating tomorrow," Bahra told a news conference.

Turkey's state-owned Anadolu news agency said the Turkey-backed Syrian National Army had taken the town of Tel Rifaat from the Kurdish YPG militia and was continuing to advance in outer areas of the district.

Rebel sources and an Aleppo resident said the Kurdish YPG group was pulling out of the city's Sheikh Maqsoud district under a deal with rebel forces. The YPG had long held the Kurdish-majority neighbourhood in Aleppo.