yazidi refugees flee Iraq
Displaced people climb on a truck on the outskirts of SinjarReuters

The United States has broken the Islamic State siege at Mount Sinjar and helped evacuate the thousands of Yazidis trapped there, according to US President Barack Obama.

"The situation on the mountain has greatly improved," he said during a televised address. "No rescue mission is needed and it is unlikely to need more humanitarian airdrops there. I could not be prouder of the men and women of our military who carried out this humanitarian operation."

The US and Britain called off a military mission to rescue thousands of Iraqis stranded on northern Iraq after special forces on the ground found their condition was better than expected.

The ethnic and religious minority, who fled a siege by Sunni militants in Sinjar, received US airdrops of food, water and medicine for days.

Obama stressed the situation remained "dire" for religious minorities in Iraq and said US forces would continue airstrikes to protect "our people and facilities in Iraq".

The US president also urged Iraqis "to come together... by seizing the enormous opportunity of forming a new, inclusive government with prime minister-designate Haider al-Abadi".

Al-Abadi was nominated prime minister instead of the incumbent Nouri al-Maliki by Shia parties and was asked to form a new government by Iraq's president, Fuad Masum.

Obama said he is "moderately hopeful" that the government is moving in the right direction.

Earlier, the Pentagon said the team on Mount Sinjar found a situation less desperate than the administration initially thought.

"There are far fewer Yazidis on Mount Sinjar than previously feared," said Rear Admiral John Kirby, the Pentagon press secretary.

He credited "the success of the humanitarian air drops, air strikes on [Isis] targets, the efforts of the Peshmerga [Kurdish guerillas] and the ability of thousands of Yazidis to evacuate from the mountain each night over the last several days".