The Islamic State in Iraq and Syria (ISIS) has declared the establishment of an Islamic state in the areas it controls and demanded allegiance from other Muslim groups worldwide.
The Sunni militant group proclaimed its leader, Abu Bakr al-Baghdadi, as "caliph" - the head of the state, and said the "caliphate" stretched from Aleppo in Syria to Diyala in Iraq.
ISIS spokesman Abu Muhammad al-Adnani said in an audio recording on the first day of Ramadan "He is the imam and khalifah (caliph) for the Muslims everywhere. His (al Baghdadi's) authority has expanded over wide areas in Iraq and Sham (Levant). The land now under his leadership spreads from Aleppo to Diyala".
He added "The legality of all emirates, groups, states and organisations becomes null by the expansion of the caliph's authority and the arrival of its troops to their areas".
"Listen to your caliph and obey him. Support your state, which grows every day".
Al-Adnani said that with the establishment of the caliphate, the group was changing its name to just the Islamic State, dropping the mention of Iraq and Syria.
Charles Lister from the Brookings Institution in Qatar called the declaration the "biggest development in international jihad since September 11th".
ISIS fighters overran the Iraqi city of Mosul last month in a lightning offensive and have since been advancing towards Baghdad. In Syria, they have captured territory in the north and east, along the frontier with Iraq.
ISIS's declaration comes as the Iraqi government is battling to wrest back some of the territory it has lost to the jihadist group in recent weeks.
Multi-pronged attack by Iraq military
On Sunday, Iraqi helicopter gunships struck suspected insurgent positions for a second consecutive day in the northern city of Tikrit, the birthplace of Saddam Hussein, around 80 miles north of Baghdad.
The Iraqi military launched a multi-pronged attack spearheaded by ground troops backed by tanks, warplanes and helicopters.
The insurgents appeared to have repelled the military's initial push and remained in control of the city on Sunday, but clashes were reportedly taking place in the northern neighbourhood of Qadissiyah.
Iraqi army spokesman Qassim al-Moussawi told reporters government troops were in full control of the university and had raised the Iraqi flag over the campus.
"It is a matter of time before we declare the total clearing of Tikrit" he said.
Jawad al-Bolani, a security official in the provincial operation command, said the US was sharing intelligence with Iraq and has played an "essential" role in the Tikrit offensive.
Washington has sent 180 of 300 American troops President Barack Obama has promised to help Iraqi forces. The US is also flying manned and unmanned aircraft on reconnaissance missions over Iraq.
Meanwhile, more than €200,000 in Irish aid is to be sent to Iraq today. The money will be used to provide food and shelter for thousands of refugees, many of whom are children.
Minister Trade and Development Joe Costello says it is our duty to help.
