Former Idaho representative George V. Hansen, who for two years has successfully delayed serving a 5- to 15-month prison sentence for violating the Ethics in Government Act, must report tomorrow to the federal prison camp in Petersburg, Va., a federal judge here ordered yesterday.

U.S. District Judge Joyce Hens Green, who had again stayed Hansen's sentence on Monday to allow him to appeal her decision denying a new trial, agreed with arguments by government prosecutors that under a recent decision by the U.S. Court of Appeals here she did not have the authority to grant a stay.

Green, who was unusually curt in addressing Hansen's attorney, Nathan Lewin, also denied the former seven-term Republican legislator's request to be released on bail.

"Defendant's appellate issues are not substantial," Green said, turning aside one of Lewin's arguments that Hansen should qualify for bail. Deflecting another of his contentions -- that the matter could be moot by the time the appeals court rules -- Green said the appeals court, which previously denied an appeal by Hansen, would have sufficient time to rule before he completed his prison term.

Green then reimposed the deadline for Hansen to surrender at Petersburg, at 3 p.m. Friday, which she had set this week and then stayed.

When Lewin asked for an additional week for Hansen, 55, to report, Green replied that the deadline she set "is the order of this court, good day," and quickly left the courtroom.

The only public official ever prosecuted under the Ethics in Government Act of 1978, Hansen was found guilty in April 1984 by a federal jury here of failing to record $334,000 in profits and loans, including transactions involving Texas financier Nelson Bunker Hunt, on financial reports to the House of Representatives.

Hansen was convicted on four counts of making false statements, involving financial disclosure reports for 1978, 1979, 1980 and 1981, and was sentenced to four concurrent 5- to 15-month prison terms and fined $10,000 on each count.

In March, the Supreme Court refused to consider his appeal and his case was remanded to Green. On the day Hansen was to appear in court for execution of his sentence, Lewin filed a motion for a new trial, saying that new information had been uncovered that could prove that Hansen had consulted with House officials about the forms and was provided incorrect information that led to the omissions.

He also asked that the sentence be reduced.

Green denied both requests, but stayed execution of the sentence, which brought objections from the government and prompted yesterday's hearing.

Again Lewin attempted to introduce new evidence in the case, a letter from House counsel Steven Ross concerning the possibility of that body joining in the latest appeal based on the "speech or debate" privilege afforded Congress.

"Is this something new, again?" Green asked. She later refused to permit the letter to be made part of the court record.

Yesterday, Hansen, accompanied by his wife Connie, two sons and a daughter, left the courtroom without commenting on Green's ruling. He was taken by court officials to be fingerprinted and photographed in preparation for reporting to Petersburg.

Justice Department attorney Reid Weingarten said that "under the law, the judge had no choice" but to order Hansen to begin serving his sentence.

Lewin said that he will appeal Green's decision denying Hansen a new trial, but indicated that the legal papers probably could not be filed and a stay obtained from the Circuit Court before tomorrow's deadline for Hansen to enter the prison camp.

"Our main priority is to get papers together to make the best case for the Court of Appeals," said Lewin.

"If it turns out that can't be done by Friday . . . " he said, Hansen's prison stay is "not an irreversible process, as unpleasant as it is."