Islamic militant group ISIS has declared a new independent Islamic caliphate in territories under its control in Iraq and Syria.

In postings on jihadist websites and social media to coincide with the first day of the Muslim holy month of Ramadan, ISIS (Islamic State in Iraq and al-Sham) declared the establishment of a new Islamic state stretching from the Syrian city of Aleppo to the Iraqi province of Diyala.

In establishing a caliphate, the group also officially changed their name to “Islamic State” and proclaimed Abu Bakr al-Baghdadi as caliph of the new state and the “leader of Muslims everywhere”.

al-Bahdadi’s position as caliph of the new state is a direct challenge to the supremacy of Ayman al-Zawahiri-led al-Qaeda as the leading Islamist organisation, as the Islamic State said in their announcement:

We clarify to the Muslims that with this declaration of khilāfah, it is incumbent upon all Muslims to pledge allegiance to the khalīfah Ibrāhīm and support him (may Allah preserve him). The legality of all emirates, groups, states, and organizations, becomes null by the expansion of the khilāfah’s authority and arrival of its troops to their areas.

Meanwhile, fierce fighting continues between Islamic State militants and the Iraqi military in the northern city of Tikrit, and Iraq has taken delivery of five second-hand fighter jets from Russia, which will go into operation later this week. Embattled Prime Minister Nouri al-Maliki hopes that air power could push back the rebels and prevent them from advancing towards Baghdad.