Iraq signed the treaty on August 19, the CTBTO said in a statement, with executive secretary Tibor Toth welcoming Baghdad's decision.

"This is particularly significant given the multitude of challenges facing the government of Iraq today," Toth said.

"It is a strong political signal for nuclear disarmament and non-proliferation. My hope is that it will encourage other countries of the region and beyond to follow suit.

"With the background of the nuclear ambitions Iraq entertained in the late 1980's and early 1990's, joining the family of CTBT member states is an important political step," he continued.

Under Saddam Hussein, Iraq had sought to use its civilian nuclear programme for military ends.

Iraq is the 179th country to sign the CTBT, which bans all nuclear explosions.

A verification regime is being built to monitor compliance with the treaty.

A total 337 facilities worldwide are planned to monitor above ground, below ground and beneath the sea for any sign of a nuclear explosion.

The CTBT has been ratified by 144 countries. However, in order to come into effect, it must be ratified and signed by 44 countries listed in the so-called Annex 2 to the CTBT. These states participated in the treaty's negotiations in 1996 and possessed nuclear power or research reactors at the time.

So far, 35 of the Annex 2 states have ratified the treaty, but nine have yet to do so, namely China, the Democratic People's Republic of Korea (DPRK), Egypt, India, Indonesia, Iran, Israel, Pakistan and the United States.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.