US-backed Syrian fighters have cut the last main road out of Raqqa, the de-facto capital of the Islamic State of Iraq and the Levant (ISIL) group, according to Kurdish military sources and a Britain-based monitor.

If confirmed, it would be a major advance for the Syrian Democratic Forces (SDF), a US-backed mainly Kurdish Syrian group, in its phased push to surround and ultimately capture Raqqa.

The SDF said its forces have cut the highway between Raqqa and Deir Az Zor province.

"Cutting the road between Raqqa and Deir Az Zor means that practically the encirclement of Daesh capital is complete by land," the Kurdish military sources told Reuters, using the Arabic acronym for ISIL.

Air strikes by the US-led coalition have also destroyed the bridges across the Euphrates River to Raqqa, according to the monitor, the Syrian Organisation for Human Rights.

'Wait and watch' approach

Reporting from the Turkish-border town of Gaziantep, Al Jazeera's Natasha Ghoneim said the major parties involved in the conflict are taking a "wait and watch approach" to see what US President Donald Trump will do.

Last month, the Pentagon submitted a proposal to the US administration on how to speed up the fight against ISIL, also known as ISIS.

In a joint address to Congress last week, Trump said that he had directed the defence department to develop a plan to "demolish and destroy" ISIL.

In the last week, the SDF took control of a major highway near the city of Al Bab.

The highway allows basic necessities to be transported as far east as Raqqa.

Syrians living in the city of Azaz near the Turkish border told Al Jazeera that they are worried about the cost of goods.

"The prices are getting higher. The goods are fewer. We're being controlled by the traders. We're forced to fight," Mohamed Ahmed, Azaz resident, said.

More than 66,000 people have been forced to flee fighting in northern Syria, according to the UN.

A petrol-station worker expressed fear that the cost of fuel will go up.

"Today, a barrel of diesel is $122. There's a chance it'll increase to $130. The vehicles run on diesel. The bakery runs on diesel. So, prices will go up," Abu Mahmoud said.