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Kurdish Iraqi peshmerga forces deploy their troops and armored vehicles on the outskirts of Kirkuk, Iraq June 12, 2014. Image Credit: AFP

Koban, Iraq: Iraqi Kurdish forces battling Islamic State militants managed on Thursday to open up a key corridor so that thousands of people from the country's Yazidi minority who have been trapped on a mountain can flee, said a senior Kurdish official.

The development was an incremental step in the battle to retake the town of Sinjar, at the foothills of the mountain by the same name, which fell to the Islamic State group in early August.

The Kurdish peshmerga troops, backed by US-led coalition airstrikes, launched the operation to retake Sinjar on Wednesday.

Masrur Barzani, chancellor of Kurdistan Region Security Council, said the Kurdish forces advanced in battle, establishing the passageway to the mountain on Thursday.

He emphasised that Iraqi forces were in no way part of the operation.

"We asked the Iraqi government to provide the ammunition needed for this operation. Unfortunately they did not send the ammunition and their contribution was nothing, to be quite frank with you, especially for this operation," Barzani told The Associated Press in Dohuk, in Iraq's Kurdish region.

Tens of thousands of Yazidis became trapped on the mountain in early August, when the IS extremists captured the towns of Sinjar and Zumar, prompting the exodus.

Thousands stuck on mountain

Many were eventually airlifted off the mountain or escorted by a passageway through Syria back into Iraq, where they found refuge in the Iraqi Kurdish semi-autonomous region.

But thousands remained stuck on the mountain.

"A corridor has been opened to evacuate those people," Barzani said. Yazidis follow an ancient religion with ties to Zoroastrianism.