The spokesman for the Libyan diplomatic mission here maintained yesterday that the $220,000 his government paid Billy Carter this year "will be treated like any other loan" although the loan papers have yet to be signed.

Ali Houderi, spokesman for the Libyan "People's Bureau" here, said bank officials in Tripoli still "have all the papers" involved in the arrangement whereby Carter got the money.

Billy Carter disclosed the payments -- a $20,000 installment in January and $200,000 more in April -- when he registered as a foreign agent for the Libyan government this week under a court order obtained by the Justice Department.

Justice Department lawyers characterized the payments as "compensation" for Carter's promotional work on behalf of the radical Libyan government of Col. Muammar Qaddafi in 1978 and 1979. They said Carter was also "held out by Libyan officials to the U.S. business community as a commercial intermediary through whom U.S. business entities could deal with Libya."

Billy Carter, however, said the cash provided to him "was a loan and not a gift."

"The people from Libya are friends of mine," the president's brother said early yesterday in a television interview with ABC. "I got it [the money] from them because I couldn't get it from a bank."

He indicated that he had been hard pressed for funds because of his controversial ties with the Libyans. He said he had lot the lecture-circuit engagements that used to provide him with income earlier in the Carter administration.

Carter would probably not have to pay income taxes on the money if it is a loan or gift, but he would if it were compensation for services rendered.

So far, neither Carter nor the Libyans have given any indication when the "loan" is to be repaid or what the interest rates will be. Houderi said he was not familiar with these details.

"I think he [Carter] listed all his property as collateral," Houderi told a reporter. "He was supposed to get $500,000, but because of bureaucratic problems, he did not get all of it." He said a representative of the Foreign Libyan Bank in Tripoli had been scheduled to come to the United States last month "and finish this deal," but the trip did not materialize. Houderi said he did not know why.

Justice Department officials, meanwhile, were reportedly planning to check on the details of a proposed deal that Carter presented to the Charter Co. of Jacksonville, Fla., when he told executive there that he might be able to get their Charter Oil Co. subsidiary a bigger allocation of Libyan oil.

Charter Oil had been getting 100,000 to 125,000 barrels a day from the National Oil Crop. of Libyan for a huge refinery in the Bahamas in which it bought a half interest last year, but was cut back starting May 1 to 60,000 barrels a day. Carter said in his registration statement that he expected to get a commission from charter Oil if its Libyan oil allocation were increased.

Charter Oil officials, however, have said that Carter did not contact him until this year. Carter said he and a colleague, Henry R. Coleman, first broached the idea to Libyan officials a full year earlier, in March of 1979. That was when Charter initiated its purchase of the Bahamian refinery and the otehr properties of the Carey Energy Co., which was deeply in debt to the Libyans.

One of Carter's lawyers, Stephen J. Pollak, said yesterday he was not aware of any other instances in which Carter undertook to act as an intermediary between Libya and U.S. companies.

Billy Carter had hired Pollak and former Watergate prosecutor Henry S. Ruth on June 11 at the suggestion of White House Counsel Lloyd N. Cutler. Cutler said yesterday that Billy Carter "happened to be" at the White House three weeks to a month ago and informed Cutler that he was being interrogated by the Justice Department about his failure to register as a foreign agent.

Cutler said he merely told Carter to get a lawyer right away. "Anybody under interrogation about an alleged violation of law needs a lawyer," Culter said. "I think that's obvious."

As the president's lawyer, Culter said he was periodically advised by Pollak and Ruth "of what was happening" so that the White House would not be caught unawares if the matter became public.

Cutler declined to say what, in turn, he told the president, but the White House counsel emphasized that the details in the registration statement filed Monday by Billy Carter "were not known, even by me, until the [Justice Department] complaint was filed."

The White House has said that President Carter did not know about Billy Carter's receipt of $220,000 and other payments from the Libyans until Monday.

The president's brother is not the only registered Libyan foreign agent with ties to Carter and his administration Richard C. Shadyac, a Washington lawyer who receives $4,000 a month from Libya a to chair the Arab-American Dialogue Committee, has been asked by Franklin Lopez, director of ethnic affairs for the Carter-Mondale Committee, to submit names for a possible Arab-American campaign committee.

Lopez said yesterday that White House ethnic coordinator Steve Aiello "knows Shadyac very well." Last month, Shadyac said he had been asked to head of Carter-Mondale effort to drum up Arab-American votes.

Carter-Mondale campaign committee chairman Robert S. Strauss said yesterday in a statement that the campaign still has no such committee and that the contact with Shadyac had taken place "without proper authority."