BUCHAREST, Romania (AP) _ Copies of secret police files show with chilling clarity how a paranoid state spied on its citizens with telephone taps, mail intercepts, photographic surveillance and paid informants.

The copies, obtained by The Associated Press, record 12 years in the life of Doru Pavaloaie, 48, an economist for a bus company who was denounced by a schoolmate because he wanted to leave the country.

The documents detail a pervasive system of internal espionage by the Securitate security agents of Communist dictator Nicolae Ceausescu, who was ousted and executed by the December revolution that ended his 24-year rule.

Pavaloaie's'file began on July 13, 1977, after his chance encounter on the streets with an old classmate, a man with whom he felt comfortable talking about his wish to move abroad, the lack of freedom in Romania and his demand that ''Ceausescu must give us food.''

The schoolmate, however, was a paid informant codenamed Geamparu who denounced Pavaloaie in a document that also made allegations about the premarital sexual activity of Pavaloaie's first wife and referred to the wealth of her parents and her relatives in West Germany.

Geamparu identifies himself in the document as a ''former school colleague'' of Pavaloaie.

''Doru Pavaloaie does not have a job and lives like a parasite. Since the very beginning of the marriage both of them have wanted to leave the country'and go to Germany to his wife's relatives,'' he wrote.

Pavaloaie, in a telephone interview from his home in Focsani, 120 miles north of Bucharest, said he later began to suspect his old friend was an informer.

''I suspected him because the security services during interrogations used some of my words when I talked with Geamparu,'' said Pavaloaie.

Early on the morning of Dec. 22, just hours after Ceausescu was overthrown, Pavaloaie was among people occupying security forces headquarters in Focsani.

Beneath the headquarters, the revolutionaries found an underground bunker with electronic eavesdropping devices, arms and ammunition, and boxes of security files stacked nearly to the ceiling.

Pavaloaie said there were files on roughly half the adult male population of the city of 100,000 people.

One concerned Pavaloaie himself, and he took it home to have the documents photographed by free-lance journalist Livia Axente, who traveled to Bucharest to make the copies available to journalists Monday at Pavaloaie's request.

''I wanted to give my name to American journalists in case something happens to me,'' Pavaloaie said.

He said he was frightened because army officers came to his house on Sunday, told him he could make copies if he wanted to, but that he had to return the file to the security headquarters.

Inside his file, which contained three ledgers as thick as a fist, he found reports from eight informers, including Geamparu, the record of telephone taps, copies of intercepted letters addressed to him, and photographs of himself taken clandestinely.

Over the years, Pavaloaie said he began to believe he was under surveillance.

''I felt something was happening with my phone lines and when I walked down the street I felt like somebody was watching me. But I couldn't imagine it was really happening,'' he said.

Pavalasie said he had known Geamparu, who was identified in the file by his real name, since his schooldays and that the informer had made a living singing at parties and weddings.

The copies of documents from the file clearly showed the letterheads of the Department of State Security or the local security forces. They were clearly marked ''Socialist Republic of Romania, Internal Affairs Ministry, Information File for Doru Pavaloaie.''

The files outline in detail how the web of surveillance spread from the original target to all his friends and acquaintances.

They show the paranoia of a state that felt a need to listen to private telephone calls, read the mail of its citizens, follow then, photograph them, investigate them, interrogate them and recruit their friends as informers.

The story of Pavaloaie also points to the twists in revolutionary Romania.

Axente said Geamparu is a man who ''really helped'' the revolution, a man who used the amplifier he uses to sing at parties to rally the people on Dec. 22. So far, said Axente, nobody has confronted Geamparu about his past as an informer. He said that people are too afraid, too uncertain about the political climate to denounce Geamparu.

Pavaloaie said he wanted to make the documents public as a way both to protect himself and to expose a system that so brutally violated his privacy.

''I saw all those young children killed by Ceausescu. They were only children and we are older men and we must fight to final victory,'' he said.