A day after a months-old siege on Mount Sinjar was broken, Kurdish peshmerga forces launched another offensive from Rabia, on the Syria border, to further clear the area.
"Peshmerga forces launched a new offensive south of Rabia to Mount Sinjar" at 8:00 am (0500 GMT), the Kurdistan Regional Security Council (KRSC) said in a statement.
The KRSC is headed by Masrour Barzani, who is the autonomous Iraqi Kurdish region's intelligence chief and also the son of Kurdish regional president Massud Barzani.
It said peshmerga forces took complete control of a number of villages north of the vast mountain range, a 60-kilometre-long (40 miles) ridge in northwestern Iraq.
Fighters and civilians from the Kurdish Yazidi minority had been trapped atop the mountain since September.
The Kurdish statement said the aim of the operation, which began on Wednesday, was to reconquer territory covering around 2,100 square kilometres (800 square miles).
Barzani has described the operation, in which he said 8,000 peshmerga are involved, as the biggest and most successful so far against IS jihadists.
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There are other groups involved in the operation, such as the Syrian Kurdish YPG group which is also leading the battle in the town of Kobane, on Syria's border with Turkey.
Among the other outfits who have had a presence on the mountain or around it are the armed wing of Turkey's Kurdistan Workers' Party (PKK) and a local Yazidi offshoot known as the YBS.
The YPG issued a statement on Friday saying they were moving south and taking villages on the Iraqi border back from IS to connect with PKK and YBS forces moving north.
Their aim is reopen the corridor that saw biblical scenes in August when tens of thousands of Yazidis fled after a first siege of the mountain in August.
The peshmerga also said they were approaching the town of Sinjar, which lies on the southern side of the mountain.
On Friday, local residents reported that peshmerga forces were closing in on Tall Afar, pounding IS positions with artillery and forcing civilians and fighters to flee.
Tall Afar is a large town located between Sinjar and the jihadists' main hub of Mosul. Huge numbers of Shiites and Turkmens had to flee the town in June.