House investigators pursing the South Korean influence-buying scandal yesterday began interrogating former ReP. Richard T. Hanna (D-Calif.) about his dealings with Tongsun Park, according to sources familiar with the investigation.

Hanna, who served in the House from 1963 to 1974, was named an unindicted co-conspirator when Park was indicted last month on charges of trying to bribe members of Congress.

Sources said the investigators questioned Hanna about his involvement in Park's business as a rice broker. Park used millions of dollars in his commissions from the sale of American rice to South Korea to finance his influence-buying effort in the Capitol, according to the indictment.

Park illegedly was one of several South Koreans here who used lavish parties, cash payments, and business deals to win support in Congress for their government.

Meanwhile, a Los Angeles lawyer, Richard DeSantis, said yesterday that he was dispatched to London last summmer by the House Committee on Standards of Official Conduct, which is probing the House's Korean connection, to seek out Park and arrange his return to the United States.

The committee chairman, Rep. John Flynt (D-Ga), denied that assertion.

Flynt said DeSantis had proposed such a mission to committee investigators, and had received a reply along the lines of "anything you can do would be fine."

But Flynt said DeSantis was not authorized to represent the House or the committee.

Park left London last month to return to Seoul, where he has resisted various official requests that he come back to the United States to cooperate in the Kortan investigation.

The State Department said yesterday that Secretary of State Cyrus R. Vance will meet today with the South Korea foreign minister, Park Tong-chin, at the South Korean government's request, to discuss Park's status.

In the Senate yesterday, Sen. Adhai Stevenson (D-III) announced that he had retained Victor H. Kramer, director of the Institute for Public Interest Representation at Georgetown University Law School, to head an investigation of possible Senate involvement in the Korean influence-buying program.

Kramer, 64, will work on a part-time basis for Stevenson's Ethics Committee, which is directing the Senate's portion of the Korean probe.

The committee undertook its own investigation late this summer after members received scattred evidence that some senators may have received illegal cash or favors from South Korean operatives.

The sparkplug behind the Senate probe has reportedly been a first-year Republican, Harrison Schmitt of New Mexico. Schmitt reportedly pushed a somewhat reluctant Stevenson into going ahead with an independent investigation of the Senate.

Schmitt said yesterday, at a press conference called to announce Kramer's appointment, that there is yet no hard evidence of improper efforts to influence senators.