US attacks IS with 20 air raids in 24 hours: Centcom

Washington (AFP) - US warplanes kept up air raids against Islamic State militants near a contested town on Syria's border with Turkey on Tuesday, part of more than 20 air strikes in 24 hours in Syria and Iraq, the Pentagon said.

In one of the heaviest rounds of bombing since Washington expanded its air war against the Islamic State (IS) group into Syria a week ago, American fighter jets and drone aircraft carried out 11 strikes in Syria and 11 raids in Iraq on Monday and Tuesday, US Central Command (Centcom) said in a statement.

American aircraft hit IS fighters near the Turkish border in an area east of Ain al-Arab, known as Kobane in Kurdish, which has come under mounting threat from the jihadists.

Three strikes near Kobane "destroyed" an IS artillery piece, damaged another and destroyed two rocket launchers, said Central Command, which oversees American forces in the Middle East.

US forces started targeting the IS group around Kobane over the weekend after urgent appeals from Kurdish leaders for help to defend the town.

In northeast Syria, US forces conducted five air raids near the Iraqi border area of Sinjar, targeting an artillery piece, a tank, three armed vehicles, an observation post and four IS "fighting positions," it said.

In eastern Syria, US aircraft carried out two bombing raids near Dayr al-Zawr, destroying an IS armored vehicle and another vehicle. And northeast of the city of Aleppo, one bombing run destroyed four IS buildings, Centcom said.

In Iraq, where Kurdish forces have launched an offensive against the IS group on three fronts, US military aircraft carried out seven strikes in the country's northwest -- two near Mosul dam, one northwest of Baghdad and one in west Fallujah, according to Central Command.

The seven raids in the northwest destroyed an IS armored vehicle, two transport vehicles, and four armed vehicles while damaging another, it said.

Around Mosul Dam, two strikes destroyed an IS position and an armed vehicle. Northwest of Baghdad, one airstrike destroyed an IS armed vehicle while another strike in west Fallujah struck an IS checkpoint, it said.

All US aircraft safely left the area safely after the air raids, it said.

Human rights monitors say the US air raids have killed and wounded civilians in Syria over the past week but the Pentagon has said it has been unable to confirm the reports.

US planes have flown roughly 4,100 sorties in the air war against the jihadists in Iraq and Syria since August 8, including surveillance flights, refuelling runs and bombing raids.