Rep. Charles C. Diggs Jr. (D-Mich.), currently on bond while appealing his conviction last year on mail fraud and other charges, asked the federal court here yesterday to let him make a 20-day, 10-city congressional tour of Africa and Europe.

Diggs is vice chairman of the African subcommittee of the House Foreign Affairs Committee. He said that he needs to visit the cities on various items of official business ranging from "exploring developments regarding the Sanelian countries" in sub-saharan Africa to "talks with the foreign ministry about Rhodesia-Zimbabwe accords" in London.

Under terms of his appeal bond since his conviction on Oct. 7, 1978, Diggs is limited in his movement and must obtain permission from the U.S. District Court before he can leave the country.

Diggs was convicted by a federal court jury on 29 counts of mail fraud and illegally diverting more than $60,000 of his congressional employe's payroll to his personal use.

Despite the conviction, he was overwhelmingly reelected a month later by voters in his Detroit district and maintained many of his committee positions in Congress.

Shortly after his reelection, Diggs was sentenced by U.S. District Judge Oliver Gasch to a maximum of three years in prison.His case is under review by the U.S. Court of Appeals here.

Attorneys for Diggs filed his request to travel to Africa and Europe late yesterday. It was not known when Gasch will rule on the matter.

The request included a copy of a letter dated Oct. 9 from Diggs to Foreign Affairs Committee Chairman Clement H. Zablocki (D-Wis.), asking for authorization to travel to the 10 African and European captials from Oct. 24 to Nov. 12.

A proposed itinerary also attached to the travel request show stops in Madrid; Algiers; Niamey, Niger; Ougadougou, Upper Volta; Bangui; Central African Republic; Doula, Cameroon; Santa Isabelle, Equatorial Guinea; Lagos, Nigeria; Freetown, Sierra Leone, and London.

Diggs, one of the most widely traveled members of Congress in past years, noted in his letter to Zablocki that some of the African nations on his itinerary have not been visited by a member of Congress since the early 1970's.

"In the Central African Republic," he said, for example, "the change in that government's direction in view of the overthrow of Emperor Bokassa [last month] would be my objective. No other member of Congress has been there since my last visit in 1970."