Mayor Marion Barry, declaring the District of Columbia's high infant mortality rate an international disgrace, ordered the city's public health agency yesterday to produce a plan within 10 days "to reduce this rate, and reduce it fast."

In response, Albert P. Russo, director of the Department of Human Resources, said his agency already has begun work on the plan, which sets a goal of cutting infant mortality by about one-third within a year.

The mortality rate for all infants under 1 year of age in 1977 was 27.3 per 1,000 live births. Among black babies, the figure was 29.5 per 1,000. Russo said his immediate goal is to bring the latter figure down to the national average of 21 per 1,000.

In 1976, the District ranked fourth highest among major cities in nonwhite infant mortality. The ranking for 1977 has not been reported.

Barry's order to move swiftly on preparing a plan to reduce the toll was contained in a statement read by Florence Tate, the mayor's press secretary, at Russo's weekly news conference.

Washington's infant death rate, the statement declared, is at best a disgrace and at worst an act of collective criminal negligence... in the capital of the most technologically developed country in the world..."

The mayor said he will appoint a five-member blue-ribbon panel to evaluate and oversee the execution of the DHR plan. The panel will be headed by Dr. Frederick Green, social director of Childrenhs Hospital and professor of child health at George Washington University.

During his campaign for mayor last year, Barry repeatedly criticized the city's public health programs and cited the high infant mortality figures.

Public attention was focused on the infant death toll two weeks ago when The Washington Post reported the then-unofficial figures for 1977, which Russo officially released yesterday.

In releasing them, Russo and Dr. I. Blanche Bourne, deputy administration of community health defended DHR's role on two principal counts -- that not all mothers and infants are cared for by public health facilities, and that the reasources available to DHR for public health have declined in relative terms over the past decade.

During his campaign, Barry also talked of reestablishing an independent health department. His transition team said that proposal needs more study. Russo said if such a split were ordered, he would not resist.