Sen. William Proxmire (D-Wis.) charged yesterday that Bert Lance, director of the Office of Management and Budget, had "violated the terms of his confirmation agreement with the Senate" by involving himself in banking legislation while holding stock in two national banks.

Proxmire, chairman of the Senate banking committee, said in a prepared statement that Lance had sent him a letter opposing a provision of a bill designed to encourage banks to reinvest in their own communities.

Proxmire cited an agreement made by Lance at the time of his confirmation hearings that he would not involve himself in "legislation dealing with the powers, responsibilities, and duties of national banks and savings and loan associations . . ." while he has a substantial holding in national bank stock.

Proxmire said Lance told him this week that he still owns the stock.

An OMB spokesman said yesterday Lance did not participate in any way "in the formulation of the administration position on the issue raised by Sen. Proxmire."

The spokesman said the issue related more to housing legislation than banking issues.

"The letter makes clear the administration agrees with the senator on the problem of redlining but believes there might be better ways of addressing the problem," the spokesman said.