Mayor Marion Barry, head of the National Conference of Black Mayors, will leave tonight for Africa as the leader of an 18-member delegation of American black mayors attending a meeting of the World Conference of Mayors in Monrovia, Liberia, the mayor announced last night.

During his trip, the mayor will visit six other African cities, including Addis Ababa, the capital of Ethiopia, where he will meet with the city's mayor and the heads of famine relief agencies.

According to the mayor's office, the World Conference of Mayors meeting, to be held from Wednesday to Friday, will concentrate on developing mechanisms for increasing international trade and fostering a dialogue among city officials in different nations on a variety of issues.

These include mass transportation, technological exchange, energy, public-private partnerships and economic aid programs.

The mayor's office said he will leave at 10 p.m. from Kennedy airport in New York. The trip will cost $15,000, about two-thirds of which will be donated by the private sector, officials said. A spokeswoman for the mayor said a full accounting would be made after the mayor returns on Dec. 24.

The mayor's itinerary includes Dakar, Senegal, Abidjan, Ivory Coast, Nairobi, Kenya, Khartoum, Sudan and Mogadishu, Somalia.

Speaking as head of the national black mayors conference, Barry expressed the need for the officials to "seek ways to broaden their ability to gain as much as they can for their cities and states."

In Dakar, he is expected to meet with the city's mayor and to present a memorandum of understanding as a follow-up to the 1980 sister-cities agreement signed with the District.