A group led by Jordanian Islamist extremist Abu Musab al-Zarqawi has pledged allegiance to Osama bin Laden's terror network al-Qaida in a statement posted on the Internet on Sunday.

It was the group's first public admission of ties to al-Qaida, that was accused by Washington of being behind the Sept. 11, attacks on the United States in 2001.

"With the advent of the month of Ramadan and the need for Muslims to unify ranks in the face of the enemy... We announce that the Tawhid and Jihad Group, its prince and soldiers, have pledged allegiance to the sheikh of the mujahideen (holy fighters) Osama bin Laden," said the statement dated Sunday.

"Sheikh Abu Musab was in contact with the brothers in al-Qaida for eight months, exchanging points of view, then contact was interrupted only to be restored again and the brothers in al Qaida understood Tawhid and Jihad Group's strategy in (Iraq)," said the statement.

It was not possible to verify its authenticity.

Zarqawi's Tawhid and Jihad Group has claimed a series of killings, hostage beheadings and suicide bombings in Iraq and the US administration put a 25-million-US dollar bounty on his head.