BBC Online :
Kurdish sources say their forces “are advancing” in an offensive to retake Mosul dam from the Islamic State (IS) jihadist group.
A joint operation involving both Kurdish forces and US air strikes has been under way since 05:00 local time (03:00 GMT), the sources said.
The strategic dam, which supplies water and electricity to northern Iraq, was seized by the militants on 7 August.
IS has seized a swathe of territory in Iraq and Syria, displacing millions.
The reported US strikes followed nine conducted on Saturday against IS targets near the dam and the city of Irbil.
Altogether 14 vehicles manned by IS militants were hit, including armour left behind by the US forces when they left Iraq three years ago, but later seized by the militants.
The BBC’s Jim Muir in Irbil, in Iraqi Kurdistan, says there is a hope that the militants may be induced to leave the dam by the threat of extreme force.
The dam is seen as a vital target, not least because a breach of it could cause a disaster, sending a 20m high wall of water into the city of Mosul and on towards Baghdad, our correspondent adds.
Meanwhile UK Prime Minister David Cameron, writing in the UK’s Sunday Telegraph newspaper, said a “firm security response” was needed to deal with IS, involving “aid, diplomacy and our military prowess”.
The UK, Germany and other countries are currently delivering humanitarian aid for refugees in the north.
The offensive at the dam comes amid reports of massacres by IS militants.
At least 80 members of the Yazidi religious minority, who are ethnic Kurds, are believed to have been killed for refusing to convert to Islam in the village of Kawju. Women and children in the same village were reportedly abducted.
A Yazidi refugee from a different village, Moujamma Jazira, told AFP news agency that people there had also been massacred, after trying in vain to fight back.
Dakhil Atto Solo said that 300 men had been executed in his village. The report could not be verified independently.
IS is also accused of killing 700 tribesmen opposing them in Syria’s Deir Ezzor province, over a two-week period.
“Reliable sources” reported that many of the tribesmen had been beheaded, the Syrian Observatory for Human Rights said.
In Western cities on Saturday, demonstrators marched in support of Iraq’s minorities – Yazidis, Christians and others.
IS first emerged in Syria, fighting President Bashar al-Assad during the ongoing civil war there, but it has since overrun parts of northern Iraq, basing itself in the city of Mosul.
Pursuing an extreme form of Sunni Islam, it has persecuted non-Muslims and Shia Muslims, whom it regards as heretics.
