Iran has hit back at "unconstructive" Turkish allegations that Tehran's allies were violating a fragile ceasefire in Syria, accusing rebels of breaking the truce.

Iraqi forces on Thursday launched an offensive aimed at retaking towns still under the control of the Islamic State group in western areas near the border with Syria, commanders said.

Israeli Prime Minister Benjamin Netanyahu says he favors a pardon for an Israeli soldier convicted Thursday of manslaughter for shooting dead a Palestinian assailant as he lay wounded.

The U.S.-led coalition said Wednesday it has doubled to about 450 the number of military advisors assisting Iraqi troops engaged in the fight to retake Mosul from Islamic State fighters.

"We have increased the number of advise and assist forces that are there with the ISF (Iraqi Security Forces) command elements to help advise them as they move forward and to synchronize operations," coalition spokesman Colonel John Dorrian said in a video conference from Baghdad.

Bahraini authorities said Wednesday three officials have been referred to the prosecutor in connection with the investigation into a deadly attack and jailbreak at the kingdom's central prison.

More than 125,000 Iraqis have been displaced since the start in October of an offensive to retake Mosul from jihadists, the United Nations said Wednesday.

Kurdish security forces closed the Iraqi headquarters of an organization that aids members of the Yazidi religious minority, which has been brutally targeted by jihadists, the group said on Wednesday.

Tunisian security forces have dismantled a 13-member "terrorist cell" that was funneling young recruits to jihadist groups, authorities said Wednesday, as part of a growing crackdown on extremists.

An Iraqi attack helicopter crashed Wednesday south of the Mosul battlefield, killing all four crew members, security officials said.

"During an army aviation mission this morning, an aircraft crashed due to a technical failure," the Joint Operations Command coordinating the fight against the Islamic State jihadist group said in a statement.

Turkey warned Wednesday that a new round of Syria peace talks was at risk, accusing President Bashar Assad's government of violating a fragile truce it brokered with Russia last week.

The nationwide ceasefire has brought quiet to large parts of Syria, but has been threatened by ongoing fighting in the Wadi Barada region near the capital Damascus.