U.S. Secretary of State Hillary Clinton has called on African nations to cut ties with Libyan leader Moammar Gadhafi and work with the Libyan opposition.

Clinton made the remarks Monday in a speech at African Union headquarters in Ethiopia's capital, Addis Ababa.

The U.S. secretary of state urged African leaders to demand that Mr. Gadhafi accept a cease-fire with Libyan rebels and give up power. She also called on them to expel pro-Gadhafi diplomats from their countries and give support to the Libyan rebel Transitional National Council.

Clinton acknowledged Gadhafi's support for African institutions over the years, but she said “we are long past the day when he can remain in power.”

Ethiopia is the final stop on Clinton's four-nation foreign trip. The trip began last week in the United Arab Emirates, where Italy, France, and other nations pledged $1.1 billion to help the Libyan rebels.

Clinton is due to meet with Ethiopian Prime Minister Meles Zenawi, and make visits to a school, a hospital and the local headquarters of the U.S. Peace Corps before heading back to the United States on Tuesday.