ISIS militants declare Islamist caliphate in Iraq, Syria

Islamist militant group ISIS has declared that it is establishing a new caliphate, or an Islamic state, on the territories it controls in Iraq and Syria.

The group also announced that the ISIS leader, Abu Bakr al-Baghdadi, will be the caliph and leader for Muslims everywhere and would be known as Caliph Ibrahim, the BBC reports.

The announcement was made through an audio recording posted on the Internet.

The ISIS rebels demanded that all Muslims "pledge allegiance" to the new ruler and "reject democracy and other garbage from the West," the report said.

The group further said that it would now be known as "the Islamic State".

Meanwhile, Iraq's army on Saturday launched a major offensive on the northern city of Tikrit, forcing ISIS-led Sunni militants to retreat, state media said.

Thousands of Iraqi troops launched an offensive on Sunni militants in Tikrit from four directions with tanks and air power.

Reports said that the governor's HQ had been recaptured and 60 fighters from the ISIS militant group killed.

A spokesman for the rebels confirmed heavy fighting. However, he said that the attack had failed, saying they were pursuing what was left of the army offensive, the report said.

The report added that the ISIS has been successfully cleared from the city.