Bert Lance said yesterday that he spoke with President Carter several times early in 1979 about Billy Carter's financial difficulties, but Lance disclaimed any detailed knowledge of Billy's efforts to strike a business deal involving Libyan oil or any other commodity.

In a series of responses to Senate lawyers, Lance acknowledged recommending a London bank to one of Billy's associates for advice concerning international trade and finance. The former Georgia banker and longtime Carter family friend said he also put Billy's associate, Henry R. (Randy) Coleman, in touch with an Atlanta lawyer interested in commodities exports.

Lance said, however, that he had no knowledge of what came of those contacts.He said the last time he talked with Billy Carter was in February 1979 when he visited the president's brother at an Americus, Ga., hospital.

The special Senate subcommittee investigating Billy Carter and his Libyan dealings later released a letter from the Atlanta lawyer, dated March 5, 1979, saying that his group would "take care of B.L." out of their 50 percent share of any sales commissions.

The letter, from attorney Robert L. Schwind to Coleman, referred to Libya as "Sandbox" and said the commissions on the sale of agricultural commodities, consumer goods and the like would be split "50-50 between your group and my group."

"Out of our 50 percent, we shall take care of B.L.," Schwind wrote Coleman. "Out of your 50 percent, you shall take care of THE MAN."

Sources said Billy Carter was "THE MAN."

Questioned about the letter, Lance said he had never seen it and protested "it incorrectly assumes that I was in fact to receive a fee."

He said Schwind told him that if any export deals went through, "he would then discuss with me the subject of whether or not a commission would be paid . . . In actuality, there was no agreement at any time that I would be paid a commission."

Recalling his February 1979 visit with Billy at the hospital, the former director of the Office of Management and Budget said he advised Billy to take care of his health and to forget about going to Libya again soon as the president's brother was reportedly planning to do.

Lance said the president had asked him to talk to Billy who was having increasing problems with his drinking.

"I indicated to Billy Carter that, in my opinion, he needed medical help and should face his drinking problem," Lance said the statement which he made public following a three-hour session with Senate lawyers. "I also told him that he was in no shape to be off traveling to Libya or, for that matter, to any other country."

Speaking with reporters after yesterday's meeting, Lance said he replied, in writing, to more than 300 questions that were handed to his attorneys. He said he did his best to answer in good faith, but found one of the committee's lawyers "somewhat abusive to me." Asked to elaborate, Lance said the man wouldn't shake hands.

Schwind is an Atlanta lawyer who reportedly has said he has represented both Billy Carter and Gold Kist Inc., an agricultural exporter that also leases the Carter family's peanut warehouse in Plains, Ga. In January 1979, Gold Kist received a proposal from Worldwide Trading Corp. to sell Gold Kist's agricultural products to Libya with Worldwide serving as exclusive agent.

Worldwide is a small company that operates out of Schwind's law offices.

In his statement to the Senate subcommittee, Lance said he did talk to Schwind about "the general subject of commodities for export" and referred him to Coleman, who "had asked whether I knew anyone that could help in commodities exports."

Lance insisted, however, that "the conversations were relatively insignificant, and I did not attach any importance to them."

The former OMB director also said that in late 1978 or early 1979, Coleman asked him for the name of a London bank that could "answer questions about international trade and finance." Lance said he sent him to the Bank of Credit and Commerce International, a Luxembourg-chartered institution headed by a Pakistani businessman. Agha Hasan Abedi.

Lance refused to answer questions about his prior relationship with BCCI on grounds this "has nothing to do with Billy Carter's contacts or involvement with the Libyans."