Iraq's Prime Minister Nouri al-Maliki has offered air support to help the Kurdish military battle the extremist group, Islamic State, formerly known as the Islamic State of Iraq and Syria, or ISIS, after the Sunni militants seized another town in their latest offensive, forcing tens of thousands of people to flee their homes.

The Kurdish peshmerga forces have been fighting the Sunni militants since they took over parts of northern Iraq and declared a caliphate in June. According to reports, the Islamic State issued an ultimatum to ethnic Kurds to either convert to Islam, pay a security tax, get killed or leave their homes, in the towns of Sinjar, Wanna and Zumar. Iraqi air support reportedly comes as the secretary general of the Peshmerga Ministry, Jabbar Yawar, said that Kurdish fighters had recaptured the town of Wanna from the militants.

"The Peshmerga forces achieved a remarkable success and seized the town of Wanna near Mosul Dam," Yawar told the official website of the Patriotic Union of Kurdistan, according to Xinhua. On Sunday, the militants had advanced rapidly through three towns to reach Mosul Dam, acquiring a fifth oil field.

According to Reuters, which cited state television, Kurdish peshmerga officials said they had prevented the militants from taking over one of the biggest dams in Iraq, adding that the news could not be confirmed.

Kurdish forces have been fighting the Sunni militants for the control of many towns located between the province of Nineveh and the Kurdish Iraqi province of Dahuk.

According to Associated Press, or AP, the Islamic State said in a statement that it had captured many Kurdish prisoners during the clashes, and had seized a "large number" of weapons, but it could not be confirmed if the statement, which was posted on a website used by the group, was authentic.

Late on Monday, Kurdish state-media reported, according to AP, that peshmerga forces had surrounded the town of Shangal and took custody of militants who had sought refuge in the area.