Export-Import Bank Chairman John L. Moore Jr. was told a week in advance of a business meeting with entrepreneur Rupert Murdoch that the New York Post publisher was having lunch the same day with President Carter, according to a bank memo.

Murdoch was seeking a multimillion-dollar low-interest loan from the Ex-Im Bank to purchase aircraft from Boeing Co. for Ansett Transport Industries, an Australian airline in which Murdoch has a major interest.

Two days after having lunch with Carter and shortly before the New York primary, Murdoch's New York Post endorsed the president. Seven days later, after Moore pressed the bank's staff to complete research on Murdoch's loan request, the Ex-Im Bank extended a low-interest financing package to Ansett.

The bank memo, dated Feb. 12 -- a week before the Murdoch-Moore meeting -- was dictated by Boeing Treasurer Jack Pierce to a receptionist at Ex-Im Bank and addressed to Moore.

It noted that Murdoch was publisher of the Post "as well as other publications worldwide," and said: "Mr. Murdoch would like to have the meeting prior to his luncheon with President Carter, which is at 12:30 to 2 p.m. on Tuesday."

In recent interviews, Moore, a former Atlanta attorney, who was appointed to his post by Carter, has claimed that at the time of the meeting he didn't know that Murdoch was publisher of the Post or that he planned to have lunch with the president.

Yesterday, Moore said he had forgotten about the memo. "It didn't click," he said. "I must have read that thing. I feel dumb."

The circumstances surrounding the loan will be probed by the Senate Banking Committee during two days of hearings beginning Monday.

Among those scheduled to testify at the hearing is U.S. Ambassador to Australia Philip Alston, who is Moore's former law partner in Atlanta and a longtime Carter supporter. Alston had pushed hard for the Ex-Im Bank to approve the loan to Ansett.

The reason for the low-interest loan was to cause Ansett to buy the Boeing 767 wide-bodied passenger jets instead of competitive A300 planes manufactured by Airbus Industrie, a European combine.

Ex-Im Bank financing has been critical to Boeing's surging worldwide sales in recent years. For example, in 1979 Boeing had about $5 billion in foreign sales, and about half of those sales involved Ex-Im Bank loans to buyers.

On Feb. 26, after the Murdoch meeting, Moore pressed other Ex-Im Bank board members to approve a loan of $657 million at an annual rate of 8 percent for Ansett to buy 12 Boeing 767s.

The other board members refused, despite tremendous pressure from Moore, according to bank sources. A tape recording of that meeting was provided to the Senate Banking Committee.

On Feb. 28, after the Ex-Im Bank staff completed additional research requested by board members other than Moore, a more modest plan was presented to the board. After further modification, the four members of the 5-person board who were there that day voted for the loan, which amounted to about $201 million at 8 percent to finance five Boeing 767s.

But even the more modest loan package has continued to bother some board members, and they have told Senate investigators about their misgivings, sources say.

In a tape-recorded interview with The Washington Post March 25 Moore said of the meeting Murdoch, "I suppose I should of known who Rupert Murdoch was, but I did not at that time."

Of the Feb. 19 meeting, he said: "We talked for about an hour. Mr. Murdoch excused himself, said he was going to the White House for lunch. My curiosity was piqued. You know, in Washington if you say you're going to the White House to have lunch that would mean you're going to lunch with somebody on the staff.

"If you're going to see the president, you'd say so. I was curious and I asked them, Murdoch's aides, and they said, yes, he was going to have lunch with the president. Mr. Murdoch is a very sophisticated person. I rather appreciated the touch."

Moore said in the interview that he was not approached by the president or anyone else from the White House on the subject of the Ex-Im Bank loan to Murdoch.