This story was filed from outside Uganda to avoid possible censorship. Ousted president Godfrey Binaisa, who is being held under house arrest by Tanzanian troops at the state house here, has appealed to President Carter to help reverse the coup carried out by the Ugandan military earlier this week.

Although about 150 Tanzanian soldiers surrounding the hilltop statehouse have isolated him and kept him incommunicado, Binaisa managed to have smuggled past his captors a letter to Carter in which he strongly criticized Tanzanian President Julius Nyerere for "aiding and abetting the rebels" and asked Carter to "please help when there is still time."

The letter to Carter was part of a two-day interview Binaisa carried out secretly through a statehouse source with reporters from The Washington Post, The New York Times and The Sunday Tiems of London. The reporters, who were barred from the presidential residence by Tanzanian soldiers, gave the source questions for Binaisa, who provided answers on a tape recorder and also sent out a signed letter attesting that the words on the tape were his.

Yesterday, to attest to the authenticity of tape recording, the source took a picture of Binaisa in captivity with a minicamera -- provided by the reporters -- and brought out handwritten letters from the embattled president to Carter, British Prime Minister Margaret Thatcher and Sudanese President Jaafar Nimeri asking for assistance. Longtime acquaintances of Binaisa vertified the taped voice and signature.

Tanzanian troops who control Entebbe have turned all reporters away from the state house. Binaisa's aides, friends and staff at the presidential residence were forced to leave this weekend.

Binaisa, who assumed the presidency last June after the ouster of dictator Idi Amin, said in his letter to Nimeri, "I don't know where they are taking me. I don't know whether they will kill me."

There have been fears for Binaisa's life all week. The interview was the first public contact with him since last Saturday when he saw a group of British and Canadian businessmen.

Binaisa's criticism of Nyerere in identical letters to Carter and Thatcher is bound to be embarrassing to the leader of neighboring Tanzania, a longtime opponent of military takeovers.

The embattled Ugandan leader said of the two leaders: "Please make my brother Nyerere see reason by withdrawing recognition from the rebel government. His attitude is causing all democrats in Uganda and Africa great concern. Usually he heads the list in condemning military coups elsewhere but this time he has for no known reason transferred his affections to a military takeover."

The letters, which are being delivered through diplomatic channels in London, did not make any specific plea for military aid or the use of violence to counter the coup.

An American educational consultant, James Barr, who lived at statehouse for the last month until he was forced to leave yesterday, said however, that the former president "hopes he will get outside assistance." Prof. Barr supplied details of Binaisa's incarceration but he was not involved in the interview or the transmission of the letters of the leaders. The intermediary, fearing for his life, asked not to be identified.

"He talked to me about Kenya and the Sudan and the possibility of their troops coming in to restore the situation," Barr said.

The military is ruling through a commission, nominally headed by Paulo Muwenga, a civilian. Most observers feel the coup has progressed too far for Binaisa to reverse it.

Kenya and the Sudan are likely to be very wary of introducing their own troops because such a move could lead to inter-African warfare with the 10,000 Tanzanians. They are the remnant of the force that overthrew Amin.

[Reuter quoted sources in the Ugandan capital as saying the new leaders, in a meeting with Nyerere in a Tanzanian border town, have agreed to ask the Commonwealth to supervise elections in September and to appoint a civilian presidential commission that would outrank the military commission.]

In the interview, Binaisa appealed to Carter for special assistance based on the Ugandan's years as a New York lawyer before returning here last June.

"I think that as a member of the bar of one of the biggest states in the country, I am entitled to the kind of protection and persuasion which the president of the United States can muster."

He told Carter in the letter that he was a "virtual prisoner" for carrying out "the unforgivable sin" of arranging for the country's first elections in 18 years to be held in December.

"The rebels and their friends are working for former president [Milton] Obote and don't want elections because they are not sure he would be elected," Binaisa said.

Obote was overthrown by Amin in 1971 and is living in Tanzania, where he enjoys Nyerere's support. The former president says he plans to return to Uganda May 27 to campaign.

Binaisa told the reporters, "I would like President Nyerere not to let Uganda miss the opportunity of going to the polls." The sarcastically compared the country's lack of elections under Obote and Amin to the four Tanzanian elections held during that period.

Calling Tanzania "definitely biased in favor of the rebels," Binaisa said:

"I would like to see my brother Julius Nyerere stopping this kind of attitude by his troops, moving them back to Kampala, seizing the radio and hand it back to us."

The Tanzanian troops moved out of the capital, leaving it to the Ugandan military two months ago when their number in the country was halved to 10,000. Nyerere, who has maintained strict silence over the coup, has said he wants to remove all his troops by September at the latest.

Binaisa also urged the Tanzanian leader to ask the Commonwealth, the organization of former British colonies, to provide 5,000 troops to maintain peace until the elections or, failing that, to ask the Organization of African Unity or the United Nations to do so.

The president provided the reporters with a copy of a "secret" letter to Nyerere sent Thursday making similar demands and complaining that the military has refused to issue his statements.

Binaisa told the state house source that Nyerere's response through an emissary was simply to promise that his troops would protect him until a safe "house, car, driver and guard" could be found for him.

Binaisa's toughest words came in his salutation to Nimeri. Using the Portuguese slogan for "the fight continues," which has become the battle cry of African revolutions, Binaisa said; "death or no death, a luta continua."