Former representative Charles C. Diggs Jr. was arrested last night on drunk-driving charges after he was involved in an accident on Ninth Street NW that injured two persons, D.C. police said.

Diggs, 63, of Hillcrest Heights, was driving a 1984 Cadillac south on Ninth Street NW about 6:20 p.m. when his car stuck the rear of another car that was stopped in southbound traffic near D Street NW, according to police.

The driver of the car, Carolynn Joan Long, 38, of 1527 28th St. SE and her passenger, Edward Hinton, 40, of 731 Seventh St. SE, received minor injuries in the crash. They were both in satisfactory condition last night, officials at Capitol Hill Hospital said.

Police spokesman Jim Battle said that upon arriving at the scene of the accident, the investigating police officer "detected a strong odor of alcohol upon Mr. Diggs' breath," leading to his arrest and a "driving while intoxicated" charge.

Battle said Diggs also was charged with "following too close" and was released upon signing a citation requiring him to appear in D.C. Superior Court Feb. 14 to answer the drunk-driving charge.

Diggs, reached by telephone at his home , at first said he did not know anything about an arrest, then declined comment and turned the telephone over to his wife, who also refused to comment on the accident.

Diggs, a Michigan Democrat, was the senior black member of Congress when he retired in 1980 after his conviction on charges of mail fraud and filing false pay vouchers. He was only the second congressman in this century to be disciplined by the House for misconduct.

He had been charged with inflating the salaries of five staff members and using the additional money to help pay his own office and personal debts. Diggs later served seven months of a three-year sentence in a federal penitentiary.

After his release in 1981, Diggs sought an apprentice funeral director's license in Maryland. The state's Board of Morticians rejected his application, but Diggs won on appeal and now operates a funeral home.