The US-led coalition "successfully engaged multiple targets" in the Islamic State of Iraq and the Levant (ISIL) group's de facto capital of Raqqa in northern Syria, US officials said.

Coalition jets conducted at least 16 raids on Sunday, which destroyed ISIL-controlled structures and transit routes in Syria, Brett McGurk, Deputy Assistant Secretary for Near Eastern Affairs (Iran and Iraq) said on Late on Saturday.

At least 23 people were killed in the attack, including six civilians and one child, the rest were ISIL fighters, the Syrian Observatory for Human Rights reported. Dozens of people were also injured.

ISIL released a video of the aftermath, which showed children were among those injured in the US-led air strikes.

"Tonight, July 4th, coalition forces launched the most sustained set of air strikes to date against ISIL terrorists in Syria," McGurk said.

"Sixteen precision air strikes in Raqqa will further restrict ISIL's ability to operate from its self-proclaimed capital (Raqqa)".

A report released online by the Combined Joint Task Force said the operation focused on "mobility corridors used by ISIL to project their fighters and military equipment, and to destabilise the region".

'Debilitating effects on ISIL'

Thomas Gilleran, the Operation Inherent Resolve spokesperson, said the disruption of these transport and communication routes in Raqqa were conducted with the intent to maximise the impacts on ISIL.



"The significant air strikes tonight were executed to deny Daesh (ISIL) the ability to move military capabilities throughout Syria and into Iraq,” said Gilleran.

"This was one of the largest deliberate engagements we have conducted to date in Syria, and it will have debilitating effects on Daesh’s ability to move from Raqqah."

The US led air strikes, combined with ground force activity throughout northern Syria, are increasing the pressure on ISIL, the online report said.

This pressure comes on the heels of ISIL ceding over 5,000km/s of territory to anti-ISIL forces over the past two months.

Palmyra killings

The UK-based observatory reported that ISIL now controls almost half of Syria's territory after capturing the historic city of Palmyra in May.

On Saturday, ISIL released a video purportedly showing 25 Syrian government soldiers being killed by teenagers in the ancient amphitheatre of the city.

The video documented the killings that reportedly happened shortly after the group captured the city on May 21. Al Jazeera chooses not to use any visual material of the victims or the act of violence from the video.

Also on Saturday, government warplanes targeted ISIL in the city as clashes raged between the two sides in the suburbs of Palmyra.

The US-led coalition launched their first round of air strikes against ISIL in Iraq in August 2014 followed by air strikes on ISIL targets in Syria during September 2014.