Defense secretary Ash Carter said on Monday that a flurry of US air strikes around Raqqa, Syria, over the weekend were aimed at disrupting the ability of Islamic State fighters to respond to advances on the ground by Syrian Kurdish forces.

At least 16 air strikes were reported late on Saturday and early on Sunday, killing at least 10 militants and wounding many others in one of the largest such operations in the country to date.

An Isis-affiliated website confirmed the strikes on the centre of the city, saying 10 people had been killed and dozens wounded. It also published photographs purportedly showing victims, including two of young boys, and suggested they were civilians.

A Raqqa-based anti-Isis network said on Sunday eight civilians, including a 10-year-old child, had been killed. The report could not be independently confirmed.

The network, called Raqqa is Being Silently Slaughtered, said at least one air strike targeted a group of Isis members in the city centre. Another targeted an checkpoint and a third destroyed large parts of a brick factory.

Carter, speaking on Monday at a news conference with the French defence minister, Jean-Yves Le Drian, said strikes targeting bridges and Isis positions around its declared capital were aimed at limiting the group’s “freedom of movement and ability to counter those capable Kurdish forces”.

“That’s the manner in which effective and lasting defeat of [Isis] will occur, when there are effective local forces on the ground that we can support and enable so that they can take territory, hold territory and make sure good governance comes in behind it,” Carter said.