US-led air strikes have targeted oil refineries controlled by the Islamic State in Iraq and the Levant (ISIL) group in eastern Syria for a third day, US officials say.

Saudi Arabia and the UAE joined in the strikes by piloted and drone aircraft targeting facilities around al-Mayadeen, al-Hasakah, and Albu Kamal, the US military said on Wednesday.

At least 14 ISIL fighters and five civilians were killed in the strikes, the Syrian Observatory for Human Rights reported. 

Only hours later after the raids, David Cameron, the UK prime minister, told the UN General Assembly that Britain should join the US-led air strikes against the ISIL in Iraq, adding that his country's parliament had been recalled to secure approval.

"I am therefore recalling the British parliament on Friday to secure approval for the UK to take part in international air strikes against the ISIL in Iraq," Cameron told the 193-member UN General Assembly.

Oil refineries hit

In its statement on Wednesday, the US Central Command said there were a total of 13 strikes against 12 modular oil refineries controlled by ISIL fighters as well as another strike that destroyed an ISIL vehicle.

"We are still assessing the outcome of the attack on the refineries, but have initial indications that the strikes were successful," the Central Command said.

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Modular refineries are prefabricated and constructed off-site so they can be transported and made operational quickly.

The US military said the refineries were capable of producing millions in revenue and provided fuel for the group's operations.

"These small-scale refineries provided fuel to run [ISIL] operations, money to finance their continued attacks throughout Iraq and Syria, and an economic asset to support their future operations," the military said.

It is unclear how much crude or refined oil the ISIL is managing to sell. The group is producing less than 100,000 barrels of crude oil a day, Adam Sieminski, head of the US Energy Information Administration, said on Wednesday.

Nicholas Rasmussen, deputy director of the National Counterterrorism Centre, testified to US Congress this month that ISIL's war chest probably included about $1m a day in revenues from black-market oil sales as well as smuggling, robberies and ransom payments for hostages.

On the ground in Syria, clashes raged on Thursday around the Kurdish-dominated Syrian town of Kobane, which has been besieged by ISIL fighters for the past week.

About 150,000 people have crossed the border into Turkey fleeing the fighting. But as Al Jazeera's Stefanie Dekker reported from the Syrian-Turkish border, many residents wanted to return to Kobane to defend their town.

"A lot of the Kurds who are going back to Syria are young men who want to take the matter in their own hands and fight the ISIL on their land," she said.

Fighters evacuate

The US has launched nearly 200 strikes in Iraq in recent weeks against ISIL fighters, who have captured wide expanses of land in Iraq and Syria over the past few months.

Activists in Syria said on Wednesday that fighters of al-Qaeda's Syrian branch, the Nusra Front, were evacuating their bases and positions in the northeastern province of Idlib.

Ahrar al-Sham, one of the most influential Syrian rebel groups with ties to Nusra, was also evacuating its positions in the region.

In Raqqa, the ISIL stronghold, residents have also reported that fighters have abandoned bases, moving into residential neighbourhoods.

The Syrian government is watching with caution the latest developments in the areas that fell out of its control more than a year ago, according to one of its ministers.

Ali Haidar, Syria's minister for national reconciliation, told Reuters news agency that the US-led strikes were so far going in the "right direction" because the government had been informed before they started and they were not hitting civilians or Syrian military targets.

Source: Al Jazeera and agencies