Sen. Edward M. Kennedy (D-Mass.) and Rep. Tom Harkin (D-Iowa), expressing dismay over the recent discovery of 25 mutilated bodies in a Chilean mineshaft, called yesterday for the United States to take part in a sweeping international investigation of "over 1,5000 disappeared" persons in Chile.

In a joint statement, Kennedy and Harkin also welcomed the recent decision by the AFL-CIO and related unions in Latin America to declare a trade boycott against the South American country.

The two Democrats urged "the administration to work closely with Chilean judicial authorities, the United Nations and the Inter-American Commission on Human Rights to ensure a rapid and thorough investigation and a full accounting for the lives and safety of all political prisoners" in Chile.

"We should no longer acquiesce in (Chilean President Augusto) Pinochet's statements that the disappeared have left the country, died in battles following the coup, or are 'presumed dead,'" said Kennedy and Harkin.

The Chilean courts have announced an investigation to determine whether the 25bodies in the mine are among some 600 persons that the Roman Catholic heirarchy contends have disappeared after being detained by security forces since the 1973 military coup.

In welcoming the boycott, Kennedy and Harkin said "this drastic step was taken in response to a disgraceful Pinochet record of persistent repression of the trade union movement."

The boycott decision came at a meeting Nov. 24 in Lima, Peru, of the Regional Organization of Workers (ORIT in Spanish acronym), of which the AFL-CIO is an affiliate.

A principal force in the boycott decision was Thomas W. Gleason, the head of the International Longshoremen's Association, who visited Chile earlier this year.