US and coalition aircraft on Sunday targeted a crude oil pipeline and collection depots in Syria held by Islamic State jihadists, the American military said, in the latest bid to undercut the group's oil smuggling.

Allied fighter jets and bombers carried out 14 air raids near the eastern city of Dayr-az-Zawr since Sunday morning, including six strikes on five crude oil collection points, a pipeline, armored vehicles and a shipping container, the US military said in a statement.

The international coalition fighting the IS has sought to disrupt the group's crude oil supplies, repeatedly targeting refineries, oil tanker trucks and various makeshift depots in Syria.

The IS has made substantial profits from illegal oil sales, offering cheap prices far below the market rate. The group also relies on money from ransoms, smuggling of antiquities and extortion in areas under its control.

The US-led coalition on Sunday also conducted eight bombing runs near the northern town of Kobane, targeting Islamic State (IS) troops that have waged a months-long battle to seize the area near the Turkish border.

IS began its offensive on Kobane in mid-September and came close to overrunning the town. But Kurdish fighters, backed by a steady campaign of air strikes, have been gradually recaptured territory in the small town.

Kurdish fighters now control 80 percent of the town, the Britain-based Syrian Observatory for Human Rights said on Monday.

In Iraq, American and allied fighter jets carried out six air strikes on Sunday against the IS group in the north and west, including two raids near the al-Asad air base where US military advisers are deployed.

As of mid-December, the American-led coalition against IS had carried out more than 1,300 air raids. Washington launched the air war in Iraq on August 8 and extended it to Syria on September 23.