US warplanes renewed air strikes against ISIL terrorists near the Syrian town of Kobani, as Iraqi peshmerga soldiers prepared to reinforce their fellow Kurds in the border area, the US military said on Wednesday.

US warplanes renewed air strikes against ISIL terrorists near the Syrian town of Kobani, as Iraqi peshmerga soldiers prepared to reinforce their fellow Kurds in the border area, the US military said on Wednesday.

US fighter jets and bombers on Tuesday and Wednesday carried out eight air raids near Kobani, targeting six vehicles, a building and several ISIL fighting positions over the past 24 hours, said the military's Central Command, which oversees the air war in Iraq and Syria.

In Iraq, American unmanned drones and fighter jets conducted six bombing raids, including three near Sinjar in the north and three around Fallujah, west of Baghdad, Central Command said in a statement.

The latest air strikes came as heavily armed peshmerga forces were poised to cross the Turkish border into Kobani to help the local Kurdish militia that has held out against a relentless assault by ISIL militants for weeks.

Earlier on Wednesday, heavily armed Iraqi peshmerga fighters were set to reinforce fellow Kurds defending the Syrian border town of Kobani from ISIL.

The peshmerga were expected to follow after a convoy of trucks carrying fighters, machineguns, heavy artillery and rocket launchers crossed the Iraqi-Turkish border early on Wednesday.

"This crossing, as with the crossing of any military group to Kobani, was done in coordination with the YPG... They are the ones who make decisions on the ground," Senior Syrian Kurdish official Newaf Khalil said.

"The peshmerga will arrive soon," he said.

In central Iraq, north of Baghdad, Iraqi forces had expanded control of territory near the Baiji oil refinery and were making progress.

Iraqi forces also had advanced against ISIL militants west of Baghdad.