President Mobutu Sese Seko responded yesterday to western pressure for reform by offering a general amnesty to more than 200,000 refugees and political opponents living in exile in Angola and other African countries and Europe.

His announcement, in a speech to a political rally at Nsele near here, was viewed by political observers as a first response to demands from the United States, Canada and Western European countries that if he wants more financial aid following last month's invasion of Shaba province by Angolan-based rebels, he must liberalize his regime and end political corruption.

Mobutu also acknowledged for the first time publicly that some members of Zaire's armed forces have been extorting money from civilians and he urged the public to inform officials of such acts "to put an end to such abuses."

Mobutu did not give details of his amnesty program but said refugees could return from neighboring Angola, Burundi, Uganda, Sudan and Tanzania and elsewhere under the auspices of the United Nations High Commission for Refugees and the Organization of African Unity.

The program was expected to include Lunda tribesmen, the former Katanga province rebels who sought independence in the former Belgian Congo in the 1960s, and other political opponents of his regime. Lunda tribesmen reportedly made up the bulk of the rebel forces that invaded copper-rich Shaba last month. Although Mobutu seemed to exclude these Angola-based rebels from the amnesty, informed sources said it would be impossible to keep them out should they decide to throw away their weapons and return to Zaire.