Lebanon hosted the largest number of new refugee arrivals between January and June 2014 although Pakistan continued to host the largest number of refugees worldwide at 1.6 million, a United Nations report said Wednesday.

"With an increase of about 325,000 Syrians during the first half of the year, by mid-2014 (Lebanon's) registered refugee population passed the 1.1 million mark," it said.

The U.S. military is reviewing several incidents in which civilians may have been killed in coalition air strikes against Islamic State jihadists in Iraq and Syria, officials said Tuesday.

The comments marked the first time the U.S. military has acknowledged that the air war may have exacted a toll on civilians.

A report by the OPCW chemical watchdog has concluded "with a high degree of confidence" that chlorine gas was used in attacks on three villages in Syria last year.

At least 13 people died among the 350 to 500 casualties from the attacks, according to the report by a fact-finding mission of the Organization for the Prohibition of Chemical Weapons, obtained by Agence France Presse on Tuesday.

At least 24 Islamic State jihadists were killed in clashes with Kurdish fighters Tuesday in the Syrian town of Kobane, where a battle has raged for almost four months, a monitoring group said.

The Syrian Observatory for Human Rights said the IS militants died in firefights and ambushes by People's Protection Units (YPG) in eastern sectors of Kobane.

The French aircraft carrier Charles de Gaulle and its fleet will be deployed to the Gulf to support operations against the Islamic State group, a military news site reported on Tuesday.

The deployment of the marine battle group is due to be announced by President Francois Hollande when he gives his annual new year's speech to the armed forces onboard the Charles de Gaulle on January 14, according to the "Mer et Marine" news site.

At least 160 children died in attacks on schools in war-ravaged Syria last year and the education of 1.6 million has been cut short by the fighting, the U.N. said Tuesday.

Schools should be "zones of peace", the U.N. children's agency said, adding that pupils should be allowed to study without risking death or injury.  

The world is losing its ability to prevent conflicts and the lack of "effective leadership" has led to the worst displacement situation since World War II, the U.N. refugee chief warned Tuesday.

Antonio Guterres, the U.N. High Commissioner for Refugees, said in Ankara that the twin crises in Iraq and Syria had created a serious displacement situation and the world showed no effective leadership to address the challenges.

An Iraqi Shiite militia leader and lawmaker has credited Tehran and a powerful Iranian general with saving the Baghdad government during last summer's offensive by Islamic State group militants.

Hadi al-Ameri, a former minister who commands the Badr militia, said support from Iran and General Qassem Suleimani had been crucial after Iraqi government forces collapsed in the face of the IS assault.

Syria is facing a "medical and humanitarian disaster" after nearly four years of war have gutted the country's healthcare system, leading to a return of eradicated diseases, a group of Syrian doctors said in Paris Monday.

A lack of doctors, supplies and drugs have plunged the country back into the medical dark ages, with polio and scabies back with a vengeance as many children are no longer vaccinated, while the majority of births take place at home.

Syria has complained to the United Nations after U.S. Senator John McCain, former French foreign minister Bernard Kouchner and other prominent figures entered the country without visas.

Syria's U.N. ambassador Bashar Jaafari said in a letter to the Security Council that countries must take "immediate measures" against nationals who travel to his country illegally.