The United States has accused the Syrian military of carrying out air strikes to help Islamic State fighters advance around the northern city of Aleppo, messages posted on the U.S. Embassy Syria official Twitter feed said.

"Reports indicate that the regime is making air strikes in support of ISIL's advance on Aleppo, aiding extremists against Syrian population," a post on the U.S. Embassy Syria Twitter account said late on Monday, using an acronym for Islamic State, which is also known as ISIS.

Islamic State fighters pushed back rival insurgents north of Aleppo on Sunday near the Turkish border, threatening their supply route to the city, fighters and a group monitoring the war said. Fighters from Levant Front, a northern alliance which includes Western-backed rebels and Islamist fighters, said they feared Islamic State was heading for the Bab al-Salam crossing between Aleppo and the Turkish province of Kilis.



Syrian officials have previously dismissed as nonsense allegations by Washington and Syrian opposition activists that the Syrian military has helped Islamic State's fight against rival Syrian insurgent forces.

"The Syrian army is fighting Islamic State in all areas where it is present in Syria," a military source said.



The United States suspended operations in its embassy in Damascus in 2012 but still publishes messages on the embassy Twitter feed.



The account said Syrian President Bashar al-Assad had long lost legitimacy and "will never be an effective counterterrorism partner."



Assad and Syrian officials have frequently called for international cooperation to fight jihadists in Syria. Damascus has described all insurgents fighting against it as foreign-backed "terrorist organisations."



State news agency SANA said on Tuesday the military had "eliminated" a number of Islamic State fighters in the Aleppo countryside and that air strikes had destroyed some of the group's vehicles.



But the U.S. Twitter feed said Damascus had a hand in promoting Islamic State, an al-Qaida offshoot which has seized land in Syria and Iraq.

"With these latest reports, (the military) is not only avoiding ISIL lines, but, actively seeking to bolster their position," it said. Syria has accused its regional enemies of backing hardline insurgent groups.



The Syrian military has carried out recent air bombardments in the province, including inside Aleppo city and on the Islamic State-held town of al-Bab to the northeast, according to the Syrian Observatory for Human Rights monitoring group.



Some rebels have questioned why U.S.-led forces bombing Islamic State in Syria and Iraq have not focused on bombing the jihadists around Aleppo city.



In rebel-held Aleppo, a local council that helps run civilian affairs called on fighters to be ready for battle with Islamic State, the Observatory said on Tuesday, citing a statement.



It called on "all mujahideen" to respond to Islamic State fighters which it said were receiving "air cover from the regime."

Iraq PM: U.S.-led coalition not doing enough in fight against ISIS

Meanwhile, Iraq's Prime Minister on Tuesday accused the international coalition fighting Islamic State of not doing enough to tackle the jihadist group, and said key members like Saudi Arabia are not curbing the flow of foreign fighters to his country.

He spoke as Western and Middle Eastern countries in the coalition are meeting in Paris. They are pushing the Iraqi government to be more inclusive of its Sunni minority.

The meeting follows the Iraqi government's biggest military setback in nearly a year. On May 17, Islamic State seized Ramadi from the demoralized and disordered Iraqi army. The city is just 90 km (55 miles) west of Baghdad and the capital of the overwhelmingly Sunni Anbar province.

Since then, government troops reinforced by Shi'ite militias have been building up positions around the city. Many of Iraq's minority Sunnis dislike the Islamic State but also fear the Shi'ite militias after years of bloody sectarian strife.

Prime Minister Haidar Abadi, a moderate Shi'ite, can only persuade Sunni tribes to fight Islamic State if he demonstrates that he can control the powerful Shi'ite militias whose military muscle he now depends on.

He said he was confident those plans were "on track" and rejected suggestions that Iraq was not doing enough politically.

"To be honest, we need a lot of political work on the part of the coalition countries. We need an explanation why there are so many terrorists from Saudi Arabia, the Gulf, Egypt ... European countries. If it is due to the political situation in Iraq, why are Americans, French and German (fighters) in Iraq?" he said.

Abadi said his forces were making progress against Islamic State but needed more support from the international community.

"It is failure on the part of the world," Abadi told reporters ahead of the meeting, which ministers from 20 around countries, including Saudi Arabia and Turkey, will attend.

"The problem is not exclusively in Iraq. We are trying to do our part, but Daesh was not created in Iraq," he said referring to the Arabic acronym for Islamic State.

Abadi said Iraq urgently needed more intelligence and weapons, including anti-tank guns. He said Baghdad had received very little arms and ammunition despite coalition pledges to provide more weapons.

"Almost none. We are relying on ourselves," he said, adding that he was waiting for UN approval to buy weapons from Iran.

"The air campaign is useful for us, but it's not enough. It's too little. Surveillance is very small. Daesh is mobile and moves in small groups," he said.

U.S. Secretary of State John Kerry will attend the meeting remotely after breaking his leg on Sunday, a senior State Department official told reporters.

"This is not a business-as-usual meeting," the official said. "We're coming in the wake of the events in Ramadi. We're coming to discuss with Prime Minister Abadi his plan ... for liberating Ramadi and Anbar province."

