Three persons were arrested in Washington and five in New York yesterday in the continuing demonstrations against the South African government's policies of racial segregation and white-minority rule.

In the District, those arrested and charged with demonstrating within 500 feet of an embassy include Roger W. Wilkins, a senior research fellow at the Institute for Policy Studies and an assistant attorney general in the Johnson administration; Ralph Abernathy III, son of the civil rights activist, and Sammie Abbott, the mayor of Takoma Park.

Their arrests bring to 70 the number of persons arrested here since the "Free South Africa" movement started the protests Nov. 21.

In New York, five labor leaders were arrested in front of the South African consulate on Park Avenue and charged with disorderly conduct, bringing to 168 the number of persons arrested there in connection with demonstrations that started Dec. 3.

Meanwhile, Maryland State Sen. Clarence M. Mitchell III (D), president of the National Caucus of Black State Legislators, said that members of the organization in 42 states have agreed to seek a "statutory statement of South Africa" in their jurisdictions. Mitchel has filed legislation that, if passed, would bar Maryland from investing any more of its pension funds in firms that do business in South Africa.

On Wednesday, disorderly conduct charges were dropped against 43 New York protesters, including Rep. Major Owen (D-N.Y.), former Manhattan Borough President Percy Sutton, Bishop Emerson Moore, labor leader Victor Gotbaum and the Rev. William Sloan Coffin.

The action by Judge Arlene Silverman in Manhattan criminal court came after arresting police officers failed to appear in court to submit affidavits relaying the charges against those taken into custody.