The Kennedy Center announced yesterday a National Block Music Colloquium and Competition designed to focus attention on classical performances by black musicians, particularly of works by black composers.

Starting with a budget of $150,000, the contest will be open to pianists and string soloists and will include other minority performers as well.

Prizes will total $10,000 and regional auditions are scheduled in Atlanta, Chicago, Houston, Los Angeles, New York and St. Louis.

In January 1980 there will be master classes, the colloquium and finals of the contest -- to be followed by a concert in the Terrace Theater with the national winning pianist and string player.

The sponsor is the National Commission to Expand the Scope and Constituency at the Kennedy Center. Its chairman, Archie L. Buffkins, said he hoped that in future years the programs will broaden to include singers and wind and brass players. This intitial undertaking was limited by difficulties in raising corporate contributions from black businesses, he said.

Commission member and violinist Sanford Allen said "the problem is too large to take on all of it at once, and you have to start somewhere." Allen is to perform two new works in the Terrace Theater later this season.

According to Thomas R. Kendrick, the Center's Director of Operations and liaision with the commission, the long term objectives are:

"To identify, encourage and recognize new talent."

"To give existing music by black composers greater visibility, through requiring its inclusion as part of the competition repertoire."

"To provide local concerts that will attract audiences with more black representation."

There will be 12 winners in the regional auditions and each will receive $500 and be sponsored in a local concert. The two national winners will get an additional $2,000 each.

Other members of the music project are composers Elie Siegmeister and Ulysses Kay and Jeanne Wade Heningburg of the Alliance for Arts Education and the Friends of the Kennedy Center. Merle Montgomery of the National Music Council will administrate the competiktion.

Buffkin's National Commission is to release next week a comprehensive report with specific proposals for increasing black involvement in the Kennedy Center. The instrumentalists' competition will be included.