MANAGUA, Nicaragua (AP) _ The lawyer for Eugene Hasenfus declared to a revolutionary tribunal Thursday that his American client was innocent of terrorism and violating Nicaraguan security.

The attorney, Enrique Sotelo Borgen, also said the People's Tribunal, which is hearing the case, does not have the authority to judge Hasenfus because it ''lacks impartiality'' and was not appointed by the Supreme Court. Hasenfus, reportedly being held in a prison outside Managua, did not attend the hearing.

Sotelo Borgen said in a written statement delivered to court officials 20 minutes before the 5:30 p.m. (7:30 p.m. EDT) deadline for entering a plea, ''I come before the authorities to deny, reject, and contradict all of the concepts of the accusations formulated against my defendant by the minister of justice.''

He also said the tribunal ''are judge in part, but on the one hand they are anti-Somocistas and ... they judge my client like a Somocista.''

Somocista is a term referring to followers of former right-wing President Anastasio Somoza, who was deposed by the leftist Sandinistas in 1979.

''Until now, our client is innocent of these crimes because no sentence has been passed against him,'' Sotelo's assistant, Luis Andara Ubeda told reporters outside the tribunal office.

The defense now has eight days, beginning Friday, to present its evidence to the tribunal in a written form, according to Foreign Ministry spokeswoman Angela Sadallos. The lawyer can request a four-day extension.

Hasenfus, 45, of Marinette, Wis., was captured Oct. 5 when the C-123 cargo plane on which he was a crew member was shot down in southern Nicaragua. It carried arms and supplies for the Contras, and the Sandinistas claim the operation was run by the U.S. government. U.S. officials have denied the allegation.

Three other men aboard the C-123 were killed - two Americans and one who has not been identified.

Hasenfus has said that he participated in 10 Contra supply flights and that they originated from a U.S.-financed military base in El Salvador and a U.S.-constructed airfield in Honduras.

The New York Times reported in its Friday editions that Hasenfus said in an interview that rebel supply planes also had used a secret airstrip in Costa Rica this year.

The newspaper also quoted Hasenfus as saying that Southern Air Transport, a Miami firm, supplied hand tools and mechanics for rebel planes at air bases in El Salvador. Southern Air Transport used to work for the CIA, but company officials say it no longer does so.

Former U.S. Attorney General Griffin Bell arrived Thursday night at Sandino International Airport and said it was ''an absolute fact'' that Hasenfus was on board a plane that contained weapons destined for the U.S.-backed rebels.

But, Bell added, ''I have great reason to doubt that he is a terrorist or committed crimes that happened 110 years ago.''

Bell, an Atlanta-based attorney who is assisting Sotelo Borgen in Hasenfus' defense, said, ''Some of the (government's 12 pages of) charges are about the bad relations between our country and Nicaragua throughout history. He couldn't possibly be guilty about some of those things.''

Bell also characterized the trial as political.

''He is an absolute pawn, that is what the trial is about,'' Bell said. ''It is sort of a windfall to Nicaragua that they have him, so they can put on public display the whole foreign policy of our country to Nicaragua.''

Sotelo Borgen had refused to say in advance what plea he would enter for his client. He and Hasenfus met on Wednesday for two hours at the tribunal offices located about a half-mile from the U.S. Embassy in Managua.

It was only the second time he was allowed to meet with his client, the first American taken prisoner in the Sandinista government's 4 -year war against U.S.-supported Contra rebels.

Bell, who served as attorney general under President Jimmy Carter, volunteered last week to defend Hasenfus, but the law requires the chief defense lawyer be Nicaraguan.

Sotelo Borgen, meanwhile, said he and Bell would ''analyze the case deeply and establish a defensive strategy.''

The People's Tribunal, made up of a lawyer, a truck driver and a laborer, refused Wednesday to grant more time for preparing the case.

If convicted, Hasenfus faces up to 30 years in prison. The tribunals were set up in 1983 to try people accused of counterrevolutionary activity. Reports from human rights groups indicate most cases brought before them end in conviction.

Also attending the lawyer's meeting Wednesday with Hasenfus were his wife Sally, his brother William and an interpreter, Sotelo Borgen said.

Mrs. Hasenfus spoke briefly to reporters after the meeting. Asked if she felt optimistic, she said, ''I won't feel completely optimistic until I get him home. I am very happy I was able to meet with him. Considering the situation he is in, he is feeling OK.''

In an NBC television interview broadcast Tuesday, Hasenfus said: ''I'm guilty of everything they've charged. It's there. How can I say I wasn't carrying small arms and munitions to their resistance?''

But Sotelo Borgen later told reporters, ''It is important that he not be declared guilty on a television network.''

The Sandinistas came to power in July 1979, ending 42 years of rule by the rightist, pro-American Somoza family. The U.S. government later covertly helped form the Contra insurgency, saying it was justified because of the Sandinistas' close ties to Cuba and the Soviet Union and alleged efforts to export leftist revolution.