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.

At least 300 fighters, primarily from the Badr and Nujabaa groups, crossed late on Sunday using a dirt road to avoid the official border crossing, two Iraqi security sources said.

“These are fresh reinforcements being sent to aid our comrades on the front lines in the north,” a senior Syrian military source said, adding the fighters had crossed in small groups to avoid airstrikes.

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.

Iranian Foreign Minister Abbas Araqchi 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 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 stabilised in 2020.

Although Russia has been focused on the war in Ukraine since 2022, it retains an air base 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.

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 destabilising 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.

Airstrikes

Russia, whose 2015 entry into the conflict turned the military balance decisively in Assad’s favour continues to support the Syrian president and is analysing 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.

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 organisation 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 a string of 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.

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 press 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 Sheikh Maqsoud.