D.C. Corporation Counsel John R. Risher Jr., in a new charge against City Council Chairman Sterling Tucker, said yesterday that Tucker has violated the city's conflict-of-interest code by using his public position to obtain money from a private foundation and Howard University.

In June, Risher had accused the Council chairman of violating the city's home rule charter by working as an adjunct professor for two years at Howard University. The charter forbids the Council chairman from holding any outside salaried position.

In court papers filed yesterday, Risher said that Tucker's employment at Howard also violated the conflict-of interest law, which prohibits city officials from using their jobs for personal financial gain. Risher said Tucker's employment at Howard required him to do things that only a city official in his position could have done.

In addition, Risher said, Tucker's acceptance of $1,350 as an honorarium to speak at the Washington Workshop Foundation in 1976 was a violation of the conflict-of-interest law.

Risher said in his motion filed in D.C. Superior Court that this was a case of Tucker's use of his public office for private gain.

Harley Daniels, Tucker's lawyer, said yesterday that although he had not finished reading the Corporation Counsel's latest charges, they appeared to be irrelevant and "patently untrue as well.

"It's not relevant to this law suit because this law suit simply has to do with the enforcement of the Home Rule Act," Daniels said. "There was no alleckation of conflict of interest at the time the suit was filed and in the amendments filed since then. Jurisdiction over conflict of interest rests with the (D.C.) Board of Elections and Ethics."

The arguments by Risher, the city's top lawyer, came as he and Tucker's attorneys opened what is expected to be the final round in a simmering political and legal controversy in which Risher, a close political confidant of Mayor Walker E. Washington, has sought Tucker's removal from office.

Risher contends that Tucker, who is expected to be a tough challenger to Washington if the mayor decides to seek re-election in 1978, should be ousted as Council chairman. That, he noted, is the penalty provided for violation of the outside-earnings restrictions.

Tucker routinely has reported the outside earnings in financial reports to the city's board of Elections and Ethics. He said he has not intentially violated the law, and that he has been told that his actions are not improper.

From the beginning, the suspicions of some of Tucker's supporters that Risher's actions are politically motivated have been fueled by the broad range of the Corporation Counsel's probe.