Iraq's intelligence service said Thursday it detained 40 members of the Islamic State group as part of a major operation in Baghdad and Diyala provinces.

"The Iraqi national intelligence service, in coordination with Baghdad and Diyala security forces, carried out an operation which resulted in the arrest of 40 members of varying rank," a statement said.

Diyala is a province just northeast of the capital where IS has not had fixed positions in almost a year but has carried out several deadly suicide car bombings.

"Many bombs, suicide belts and cars used by the terrorists were seized, as well as large amounts of money they used to fund their criminal activities," the statement said.

The intelligence service said the detained IS members had requested assistance from cells in other parts of the country, suggesting the group is weakened in Baghdad.

The swoop was the continuation of an operation that had already resulted in more than 30 arrests and the dismantling of a car bomb-making cell in Baghdad in March.

Kurdish-Arab alliance pushes IS back in north Syria: spokesman
Beirut (AFP) Dec 24, 2015 - An alliance of Kurdish and Arab rebels advanced Thursday against the Islamic State jihadist group in Syria's north in a new offensive backed by US-led air strikes, its spokesman said.

Talal Sello, spokesman for the Syrian Democratic Forces, told AFP the SDF offensive was launched late Wednesday in Aleppo province.

"The battle now is aimed at the liberation of areas south of the town of Sarrin... to the Tishreen Dam" on the Euphrates River, Sello said.

Kurdish forces pushed IS out of Sarrin in July.

SDF fighters, which predominantly hail from the Kurdish People's Protection Units (YPG), had advanced to within 12 kilometres (less than eight miles) from the dam by Thursday, according to Sello.

The dam, been held by IS since 2014, helps generate electricity for large parts of Aleppo province, according to the Syrian Observatory for Human Rights.

IS also controls the Euphrates' western bank -- from the northernmost point at Jarablus, which lies on the Syrian-Turkish border, south and further east all the way to Raqa.

Manbij and Al-Bab, IS's strongholds in Aleppo province, lie west of the river as well.

Syrian forces, backed by Russian air strikes, have made gains against IS south of those towns.

"Fierce clashes are continuing along the eastern banks of the Euphrates," Observatory head Rami Abdel Rahman said Thursday.

He confirmed that the SDF had advanced along the banks, but said most of the territory captured consisted of small villages.

Sello said the SDF was receiving backing from the US-led coalition conducting an air war against IS in both Syria and Iraq.

A coalition statement Thursday said strikes conducted the previous day hit near Manbij and destroyed an IS fighting position and a logistics facility.

Formed in October, the SDF has scored a series of successes against IS in northeastern Syria and appears to be extending its operations further west.