The Iraq-based terrorist group Tawhid and Jihad, thought to be led by Jordanian fugitive Abu Musab al-Zarqawi (search) and likely responsible for many kidnappings and beheadings, declared its loyalty to Al Qaeda and Usama bin Laden over the weekend.

A manifesto by Tawhid and Jihad (search) ("Monotheism and Holy War") was posted on an Islamist militant Web site Sunday, calling for unity against "the enemies of Islam."

It said "viewpoints were exchanged" with Al Qaeda (search) eight months ago, but that the dialogue between the two groups had been interrupted.

"God soon blessed us with a resumption in communication, and the dignified brothers in Al Qaeda understood the strategy of Tawhid and Jihad," read the statement, whose authenticity could not be confirmed.

The statement ran a Quranic verse encouraging Muslim unity and said al-Zarqawi considered bin Laden "the best leader for Islam's armies against all infidels and apostates."

The Jordanian-born al-Zarqawi is suspected of about a dozen high-profile attacks in Iraq, including last year's bombing of the U.N. headquarters in Baghdad, and the beheading of numerous foreign hostages.

His relationship to bin Laden and the Al Qaeda leadership has long been the subject of considerable speculation.

Although many experts believe al-Zarqawi had longtime ties to Al Qaeda, others suspected that al-Zarqawi considered himself a rival to bin Laden for the mantle of chief defender of the Muslim faith.

The Bush administration said it was still trying to confirm the report.

"But we've always said there were ties between Zarqawi and Al Qaeda, which underscores once again why Iraq is the central front in the war on terror," White House spokesman Trent Duffy said in Washington. "It's also proof positive of why the president's firm resolve to fight terrorists overseas so we don't face them in America's neighborhoods is the only clear way to prevail."

The statement affirmed the "allegiance of Tawhid and Jihad's leadership and soldiers to the chief of all fighters, Usama bin Laden." It said the announcement had been timed for the start of the Islamic holy month of Ramadan (search) when "Muslims need more than ever to stick together in the face of the religion's enemies."

The statement also endorsed bin Laden's goal to "expel the infidels from the Arabian peninsula" — a reference to American influence in the Al Qaeda leader's native Saudi Arabia, birthplace of the Islamic faith.

Al-Zarqawi's declaration appeared two days after the U.S. government formally declared his Tawhid and Jihad a terrorist organization. The listing imposes several restrictions on the group, including a ban on travel to the United States and a freeze on the group's assets in U.S. banks.

Al-Zarqawi also was indicted in absentia Sunday in his native Jordan along with 12 other alleged Muslim militants on charges of plotting a chemical attack that could have killed thousands of people.

Al-Zarqawi and three of the others will be tried in absentia on charges including conspiring to commit terrorism, possessing and manufacturing explosives and affiliation with a banned group, according to the 24-page indictment made available Sunday to The Associated Press.

U.S. and Iraqi officials believe al-Zarqawi's movement is centered in the insurgent stronghold of Fallujah, where U.S. troops clashed Sunday with militants.

However, Tawhid and Jihad banners have been seen recently in Samarra, Ramadi and even on the streets of the Iraqi capital, Baghdad.

It appeared the announcement was aimed at enabling al-Zarqawi, who has a background as a common criminal, to profit from bin Laden's stature among radical Muslims.

Bin Laden, believed to be hiding in Afghanistan or in the border areas of Pakistan, has faded somewhat from public view and recent declarations by Al Qaeda's leadership have been made by his deputy, Ayman al-Zawahri.

The Associated Press contributed to this report.