UPDATE 2000 GMT: President Obama has ordered the deployment of another 1,500 military personnel to train and assist Iraqi and Kurdish forces.

Almost 3,000 additional US advisors and special forces have been sent to Iraq since the Islamic State’s offensive in June.

The Islamic State has seized hundreds of tribesmen from the jihadist-controlled town of al-Alam in central Iraq, accusing their leaders of plotting a rebellion, according to residents and officials.

Residents of al-Alam, about 100 miles north of Baghdad, said the Islamic State has detained as many as 500 men and boys from the Sunni Jubouri tribe since Sunday. The seizures began after youths tore down the jihadists’ black banner from a square in the town center and replaced it with an Iraqi flag.

Families and officials said they do not know if the captives are alive and, if so, where they are being held.

The Islamic State has reportedly executed more than 300 members of the Albu Nimr tribe, which is also Sunni, in western Iraq in recent weeks.

“It is clear they want to take their revenge against us like they did against Albu Nimr,” said Sheik Jabar al-Jubouri, a tribal leader from al-Alam who has fled the town.

Sources said the Islamic State has demolished many Jubouri family homes in al-Alam and are forbidding shopkeepers from doing business with the tribe’s members.

The jihadists took al-Alam during their June offensive which captured cities like Mosul and Tikrit and swept towards Baghdad. The tribesmen accepted an uneasy peace, with some tribal leaders fleeing.

The Islamic State then imposed a strict version of Islamic law, forcing women to cover their faces and setting up sharia courts.