U.S. Secretary of State Condoleezza Rice has called on members of the United Nations to move forward with reforming the world body.

She said the United Nations must be transformed to meet shared current challenges, and called on nations to ratify an anti-terrorism pact, the Comprehensive Convention on Terrorism.

She made the remarks to the United Nations General Assembly, Saturday.

She said the greatest global threats emerge within states and cross borders, including terrorism, weapons proliferation, and human trafficking.

Friday, a United Nations summit concluded with world leaders adopting moderate U.N. management reforms, which fell short of the sweeping changes called for by Secretary-General Kofi Annan.

Later Saturday, Iranian President Mahmoud Ahmadinejad is expected to explain his country's nuclear ambitions in a speech to the General Assembly.

The United States accuses Iran of having a secret atomic weapons program, but Iran insists its nuclear programs are for peaceful purposes only.