Updated

The leader of al-Qaida's Iraq arm defiantly rejected an order from the terror network's global command to scrap a merger with the organization's Syria affiliate, according to a message purporting to be from him that was posted online Saturday.

The latest alleged statement by Abu Bakr al-Baghdadi, who heads the Islamic State of Iraq, reveals a growing rift within the terror network and highlights the Iraqi wing's determination to link its own fight against the Shiite-led government in Baghdad with the cause of rebels trying to topple the Syrian regime.

In an audio message posted online, a speaker identified as al-Baghdadi insists that a merger he announced in April with Syria's Jabhat al-Nusra rebel group to create a cross-border movement known as the Islamic State in Iraq and the Levant will continue. Al-Nusra is Syria's most powerful rebel extremist group, and its head has rejected the takeover attempt.

"The Islamic State in Iraq and the Levant will continue," he said. "We will not compromise and we will not give up."

The Qatar-based Al-Jazeera TV reported late Sunday that al-Qaida leader Ayman al-Zawahiri had issued a letter trying to end the squabbling and ordering the two groups to stay separate.

Al-Baghdadi is now defying that command. In his statement, he referred to "the letter attributed to Sheik al-Zawahiri," suggesting he was calling into question the authenticity of the letter.

"I chose the command of God over the command that runs against it in the letter," al-Baghdadi said.

He urged his followers to rise up against Shiites, Alawites, and the "Party of Satan" — a reference to the Iran-backed Lebanese militia Hezbollah, which has been sending fighters to Syria to fight alongside President Bashar Assad's regime. Assad comes from the Alawite sect, an offshoot of Shiite Islam.

It was not possible to independently confirm whether the speaker was al-Baghdadi, but the man's voice was similar to that of earlier recordings.

Violence has spiked sharply in Iraq in recent months, with the death toll rising to levels not seen since 2008. Al-Qaida in Iraq is thought responsible for many of the car bombings and other violent attacks targeting the country's majority Shiites and symbols of the Shiite-led government's authority.

Iraq risks getting more deeply involved in the Syrian civil war raging across its western border.

Iraqi border posts along the Syrian frontier have come under attack by rebels, and Syrian truck drivers and soldiers have been killed inside Iraq. Iraqi fighters are moving across the border, with Sunni extremists cooperating with the rebels and Shiite militants fighting alongside government forces.

Also on Saturday, an Iranian exile group living in a camp near Baghdad airport reported multiple casualties when the compound, known as Camp Liberty, came under attack from rockets.

The group, the Mujahedeen-e-Khalq, is the militant wing of a Paris-based Iranian opposition group that opposes Iran's clerical regime and has carried out assassinations and bombings in Iran. It fought alongside Saddam Hussein's forces in the 1980-88 Iran-Iraq war, and several thousand of its members were given sanctuary in Iraq. It renounced violence in 2001.

Camp residents Kolthom Serahati and Javad Naghashan were killed and several others were wounded, according to the NCRI.

Iraqi police officials confirmed that blasts struck near the airport, though they said mortar shells were to blame.

They and hospital officials said an Iraqi was also killed, and that the wounded included nine Iranians and seven Iraqis. The officials spoke on condition of anonymity because they were not authorized to release the information.

Iraq's government wants the MEK out of the country, and the United Nations is working to relocate residents abroad. Several residents moved to Albania last month.

UN envoy Martin Kobler condemned the attack, which he said happened despite "repeated requests to the Government of Iraq to provide Camp Liberty and its residents with protective measures." He urged countries to do more to help resettle the residents abroad.

There was no immediate claim of responsibility for Saturday's attack.

A similar deadly attack in February was blamed on Shiite militants. The head of one Shiite militia, the Mukhtar Army, later that month threatened further strikes on the compound.

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Associated Press writer Sameer N. Yacoub contributed reporting.

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