Chilean President Augusto Pinochet's victory in a tightly controlled national plebiscite is likely to reverse the trend noted in recent months toward gradual loosening of human rights and political restrictions, political observers here predict.

The expection is shared by important members of the military itself, who have made known their fear that Pinochet may use the lopsided vote in his favor to justify assuming more power at the express of the military junta and the judical branch.

Statements by Pinochet at a voting night victory rally Jan. 4 indicated that he intended to put a stop to opposition political activity, which although officially outlawed for four years had been gathering momentum since July when Pinochet announced a plan calling for a partially elected legislature in 1985 or 1986.

Political repression and secret police activity have also declined motably here during 1977 and major restructing of the security police apparatus in August encouraged human rights leaders.

A prominent leader of the opposition Christian Democratic Party said the plebiscite "allowed a small political opening "for opposition activity during the 13 days between Pinochet's surprise announcement of the national consultation and the voting Wednesday."

"Now there is going to be a hardening," the Christian Democratic leader said. "You just have to read Pinochet's speeches. But that by no means we are going to give up the fight."

Pinochet received 75.3 per cent of the 5.5 million votes cast, according to the government, and 20.3 per cent voted "no" to the proposition expressing support for Pinochet.

About 100 youths chanting insults and pro-government slogans gathered outside the home of Christian Democratic Party President Andres Zaldivar shortly after Pinocher's victory rally. The mob pelted Zaldivar's house with stones, pushed down a metal gate, and damaged a car parked outside the house.

A statement by the Christian Democratic Party said the results and the procedures surrounding the voting and vote counting confirmed an earlier statement warning that "a great feaud" was in the making.

The government counted votes in secret after the initial public opening of ballots.

Pinochet said at a press conference that "some measure of order" would come as a result of the victory and that it had put an end to "thinking about election and voting."

The plebiscite also seemed to dampen expectations in well informed diplomatic circles that the four-year-old state of siege and curfew would soon be revoked in order to continue gradual improvement of relations with the United States and Chile's major trading partners in Europe, Pinochet joked with reporters about the state of emergency and said it was "very well" the way it is.

The calling of the plebiscite brought to the surface a simmering conflict between Pinochet and juanta member Gen. Gustavo Leigh, who said in a letter leaked to the press that the air force opposed the plebiscite and that its announcement unilaterally by Pinochet was a violation of junta prerogatives.

Leigh did not attend Pinochet's victory rally. In a press conference later he said he had a cold and had gone home early the day of the voting.

Leigh said his exchange of letters with Pinochet did not mean that the air force was in disagreement with the government, but he made it clear that part from the plebiscite the major issues of his dispute with Pinochet were far from settled.

He said the plebiscite results were "very good", but added, "now we must turn the page and confront the second phase, that is, the measures to be adopted within the governing junta. These will be profoundly studied."

"While there is consensus that the junta must remain united, it is also necessary that concessions be made, I believe, from other sectors," he said.

Leigh said in his Dec. 23 letter to Pinochet that the air force was concerned about some of the plans being discussed among Pinochet's advisers for after a plebiscite victory.

A reliable source outside the government said the measures worrying the air force officers included subordination of the Chilean judical branch to the presidency, increase repression of union and political party activity, and lessening of the role and influence of the other three junta members.

When Leigh's conflict with Pinochet became public, the air force general began to enjoy an unusual popularity among opposition demonstrators, who pued into the streets for the first protests against the military government. At one point opposition demonstrators chanted his name in response to government supporters' chants of "Pinochet!"

At the root of the Pinochet-Leigh disagreements seems to be postponement of a clear delineation of powers of the junta.