The US-led coalition has conducted four strikes near the Syrian town of Al-Bab, a significant move that will help Turkish forces fighting the Islamic State group there, a US official said Tuesday.

"These strikes were the result of continued cooperation with Turkey, and we saw a window of opportunity where it was in our mutual interests to get those targets destroyed," coalition spokesman Colonel John Dorrian said.

"This is something that we expect to continue doing."

Among the targets destroyed in this week's strikes near Al-Bab included IS tactical vehicles and a tactical unit.

Turkey has been fighting the Islamic State jihadist group in Syria since August, but the battle to take town of Al-Bab has proved tough and casualties there are on the rise.

Ankara has in recent weeks called for greater US support in Al-Bab in northern Syria.

Up until now, air support had been limited to surveillance and reconnaissance.

The United States is in a tricky position: Although it wants to help Turkey fight IS, it does not want Turkish forces to attack coalition-backed local Kurdish troops, who also are fighting the jihadists.