ALGIERS, Algeria (AP) -- A group of African nations pledged cooperation Thursday in rooting out terrorism and vowed to refuse safe havens, visas and other forms of assistance to terrorists.

At a four-day conference of the African Union, Sudan, Ghana and South Africa ratified an anti-terrorism pact, giving the final signatures needed to push through a convention adopted in 1999, said Algerian Minister for African Affairs Abdelkader Messahel.

Until now, only 12 of the 53 members of the African Union had ratified the document that calls on signatories to beef-up anti-terrorism laws and to "prevent their territories from being used as a base for the planning of terrorist acts." It needed ratification by 15 members to take effect.

Among the members that had already ratified it were: Algeria, Angola, Egypt, Eritrea, Kenya, Lesotho, Libya, Mali, Rwanda, Senegal, Tunisia and Western Sahara.

Officials said Burkina Faso, Ethiopia, Nigeria, Tanzania and Uganda were the next nations expected to ratify the pact, called the Convention on the Prevention and Combatting of Terrorism.

The document also calls for better exchange of information and cooperation among signatories of police and other authorities in the pursuit of terror suspects.

The conference, which started Wednesday, was organized on the anniversary of the Sept. 11 attacks to underscore the threat of terrorism in Africa.

Officials from the United States, France, Russia and various international organizations such as the United Nations, Interpol and NATO, were invited to the talks along with officials from the African member states.

A number of African nations, notably Algeria, Tunisia, Egypt and Kenya, have suffered attacks by suspected Islamic extremist groups but lack a common approach to deal with them.

Algerian President Abdelaziz Bouteflika, who opened the conference on Wednesday, vowed he was committed to continuing the international fight against terrorism.

The leader proposed opening in Algeria a center for study and research for the fight against terrorism.

Algeria, in particular, continues to be riven by a decades-old Islamic insurgency that has claimed more than 120,000 lives. The fighting broke out in 1992 after the army canceled general elections that a Muslim fundamentalist party was poised to win.

In July, Africa's heads of state transformed the weak Organization for African Unity into the African Union, in a bid to move more aggressively to address the problems of the world's poorest continent.