An anti-apartheid demonstrator threw himself in front of South African-born runner Zola Budd yesterday and prevented her from finishing the English women's cross-country race in Birkenhead, England.

Budd, now a British citizen, had just taken the lead after the midway point of the five-kilometer (3.1-mile) race when the demonstrator ran from the packed crowd, estimated at 7,000.

He landed in front of Budd, who ran off the snow-covered course when she swerved to avoid him.

Angela Tooby won the race.

Budd said, "It happened towards the end of the first lap. I saw a policeman with a truncheon trying to keep some people away. Then they came onto the course. The officers could not keep them away and I stopped.

"I was a bit frightened, but an official shielded me . . . I am very disappointed I wasn't allowed to finish the race, but I am still looking forward to running in the world championships."

Budd, 18, born on a farm near Bloemfontein, became a British citizen last year in time to participate in the Los Angeles Olympics. After a collision with Mary Decker of the United States, she finished seventh in the women's 3,000-meter race . . .

World indoor bests were reported broken in four events yesterday. In Senftenberg, East Germany, sprinter Marita Koch improved her world best in the women's 60-meter dash by four-hundredths of a second, with a time of 7.04 in the National Indoor Track and Field Championships. Also in that meet, Ulf Timmermann had a world best for shot put of 22.15 meters. His third throw of the competition outdistanced the 11-year-old mark of George Woods by 13 centimeters.

Galina Chistyakova of the Soviet Union broke the world best in the women's long jump with a jump of 23 feet 9 1/2 inches at the National Indoor Track and Field Championships in Kishenev, Tass reported. The previous best of 22-11 1/4 was set by Heike Daute-Dreschler of East Germany.

In Genoa, Giuliana Salce of Italy bettered her world best for the one-mile indoor walk in an international meet. Salce clocked 6:28.46 seconds, beating her best of 6:43.59 set in Genoa Feb. 4, 1984 . . .