* Ghosn's first news conference since arrested in Nov 2018
* Says treated brutally by Japan, had to flee to clear name
* Denies wrongdoing, says victim of a conspiracy
* Tokyo prosecutor says Ghosn's allegations "unacceptable" (Adds source, Tokyo prosecutor comments, detail, background)
BEIRUT, Jan 8 (Reuters) - Carlos Ghosn, speaking publicly for the first since his dramatic escape from Japanese justice, told reporters in Beirut he had been treated "brutally" by Tokyo prosecutors and was the victim of a conspiracy to oust him from the helm of automaker Nissan.
Wearing a blue suit and red tie and speaking defiantly, the one-time titan of the car industry told a packed news conference on Wednesday he would not have faced a fair trial in Japan and would have been tied up in appeals there for five years.
The 65-year-old fled Japan last month where he was awaiting trial on charges of under-reporting earnings, breach of trust and misappropriation of company funds, all of which he denies.
Ghosn said he had escaped to his childhood home of Lebanon to clear his name. He declined to say how he fled, noting there were conflicting stories about his departure.
"You are going to die in Japan or you are going to have to get out," he said, describing his feelings. "I felt like the hostage of a country I served for 17 years," he told reporters crowded into Lebanon's seaside Beirut press syndicate.
Others waited outside in heavy rain, including some Japanese media who had been excluded from the briefing.
"The charges against me are baseless," Ghosn added, repeating his allegation that Nissan and Japanese authorities colluded to oust him following a downturn in Nissan's fortunes and in revenge for French government interference in the carmaker's alliance with Renault.
Ghosn's news conference marks the latest twist in a 14-month saga that has shaken the global auto industry, jeopardised the Renault-Nissan alliance of which Ghosn was the mastermind and increased scrutiny of Japan's judicial system.
"Defendant Ghosn's allegations completely ignore his own conduct and his one sided criticism of the Japanese criminal justice system is totally unacceptable," the Tokyo prosecutor's office said in a statement on its website after Ghosn spoke.
Ghosn said he had no intention of merging Renault with Nissan as some in Japan feared, but wanted to put the firms under a holding company that would have maintained a balance between the French carmaker's push for a union and the Japanese company's desire to remain autonomous.
Ghosn named Masakazu Toyoda, an independent director at Nissan and a special adviser to the Japanese Cabinet; Nissans ex-auditor Hidetoshi Imazu; and the car company's former executive vice president Hitoshi Kawaguchi as the main architects of his downfall.
Imazu, Kawaguchi and officials at Nissan could not immediately be reached for comment.
"First, if he (Ghosn) has anything to say, he should do that openly in court before he leaves Japan illegally. A conspiracy story without any evidence sounds like a joke," one person referred to by Ghosn told Reuters.
Ghosn declined to name Japanese government officials he said took part in the alleged plot because he said he didnt want to embarrass the Lebanese government, but added he did not think the top level of the Japanese government was involved.
In a wide ranging presentation, Ghosn talked about his Marie Antoinette-themed wedding party at the Palace of Versailles in France and described his confinement in Tokyos main jail and the investigation launched against him.
After heated criticism of Japanese prosecutors and a point-by-point rebuttal of their allegations, Ghosn became most animated when describing how he believed the Nissan-Renault alliance had lost its way since his departure, failing to seize opportunities such as a potential tie-up with Fiat-Chrysler and falling behind in crucial success benchmarks like investment in technology, profitability and market value.
The opportunity to tie up with Fiat-Chrysler should have been unmissable for Nissan-Renault, Ghosn said, since it would have made the companies more dominant players.
How do you miss that? Its unbelievable, he said.
They said they wanted to turn the Ghosn page. Well, they have been very successful, he said, sarcastically. "What we see today is a masquerade of an alliance ... that is not going to go anywhere.
Nissan has said an internal investigation found that Ghosn had engaged in personal use of company money and had under-reported his income in violation of Japanese law.
Japan's Ministry of Justice has said it will try to find a way to bring Ghosn back from Lebanon, even though it has no extradition treaty with Japan.
Lebanon's state news agency said a public prosecutor had summoned Ghosn for questioning on Thursday.
"Why have they extended the investigation timeline, why have they rearrested me? Why were they so intent on preventing me from talking and setting out my facts?" Ghosn said of the Japanese authorities.
"Why have they spent 14 months trying to break my spirit, barring any contact with my wife?"
Tokyo prosecutors on Tuesday issued an arrest warrant for Ghosn's wife, Carole, for alleged perjury related to the misappropriation charge against her husband.
Turkish and Japanese authorities are investigating how Ghosn was smuggled out to Beirut. Interpol has issued a "red notice" seeking his arrest.
After his lengthy statement in English, Ghosn took questions in French, Arabic, Portuguese and English in a raucous 90 minute news conference that was broadcast in part by several Japanese TV networks.
(Reporting by Samia Nakhoul and Eric Knecht in Beirut; and David Dolan, Linda Sieg, William Mallard. and Maki Shiraki in Tokyo; Writing by Tim Kelly in Tokyo; Editing by Mark Potter)