Chilean President Augusto Pinochet, marking the ninth anniversary of his military government amid an economic crisis and eroding political support, today sharply attacked his critics and pledged not to alter the government's course or its authoritarian measures.

In a day of austere official ceremony and equally modest protests commenorating the military overthrow of socialist president Salvador Allende in 1973, Pinochet declared that "neither the transitory situation in the economic order nor the aggression of the enemy will divert the projects of this government."

The 66-year-old general, in his annual address, conceded that severe economic problems "have hit us hard" and that "a series of difficulties have affected the work and the hopes of many." But he rejected suggestions that his government permit more freedom and relax political restraints. He said that "all the vigor of the law" would be applied to "those who try to foment an artifical atmosphere of political agitation."

The lengthy speech broadcast on radio and television came after several months of turbulence in Pinochet's government and growing signs of dissent among key supporters in the military over the economic and political models that have long guided Pinochet's rule.

The country's business and banking sectors, which once broadly supported Pinochet, recently have exerted strong pressure on his government to alter the strict free-market, monetarist economic policy aggressively pursued for the past seven years. Once pronounced a Latin American "miracle" by its backers, Chile's economy has plummeted into a severe recession and unemployment is reported by the government at 23 percent.

In recent months, the disputes over economic policy have extended to the top levels of the administration, producing three changes of Cabinet during the past eight months and open divisions between Chile's U.S.-trained economic technicians and military leaders.

The economic problems have also helped swell traditional opposition movements and demonstrations against the government. An illegal protest march drew an estimated 2,000 persons to the center of Santiago last month, and a series of university demonstrations this week provoked the government to shut one program at a mjaor university in Santiago and call off classes at the university in the port city of Valparaiso.

Perhaps more seriously, the pressure on Pinochet from businessmen has been complemented by a splintering of his traditional backing among right-wing political sectors. Two years after promoting a new constitution and promising an eight-year transition to a conservative, "protected" democracy, some of the military's key ideological supporters have begun to complain that the expected liberalization is being resisted by the president and the armed forces.

"There has been a clear departure of supporters of the government outside of the government," said Roberto Pulido, the former head of the right-wing political movement that supported the new constitution. "The administration has shown little interest in moving forward on political matters, and there is distrust of the sincerity of some sectors. "

Pinochet sought in his address today to assuage the doubts of his political base, arguing that the economic troubles were the fault of the world recession and stressing his commitment to carrying out the slow political transition.

But his voice rose quickly when he declared that "the government has clearly determined what is the extent of legitimate political discrepancy that can exist at this time."

In clear reference to both the political opposition and human rights groups that have criticized government repression, he added, "Despite the time passed since the military coup the enemies of that time have permanently continued to agitate . . . encouraged even by the mistaken representatives of institutions of religious character."

Government supporters had expected a strong speech from Pinochet today as part of the government's effort to regain public confidence following a period of apparent instability and in decision.

Last month, faced with open differences among his ministers, Pinochet dismissed his Cabinet only four months after it had been formed. As rumors swept political circles, he then began an intensive round of meetings with business groups, military leaders and right-wing politicians in an apparent search for consensus on economic policy.

As the deliberations continued, conservatives became alarmed that the military was considering shifting to a populist, neofascist government, and supporters of the monetarist economic policy reported that Pinochet was negotiating with the more traditional economic strategists of previous democratic governments.

The new Cabinet, named two weeks ago, appeared to represent a compromise between the strict economic models and the demands of business groups. The new economics minister, Rolf Luders, declaring there would be no changes in policy, has quietly led heads of business groups to expect government action on their mounting debts, the recession and unemployment.

The result, said Jorge Fontaine, the president of the influential Confederation of Production and Commerce, is that "there has been a relaxation of uncertainty. Business has regained some confidence and is willing to give the government some time" to solve the economic problems.

The relaxation of pressure from business groups, however, has not slowed the criticism of Pinochet's political supporters, who long have been a key civilian base for the military government.

Several government supporters said in interviews this week that Pinochet has made almost no move to implement the elaborate laws required by the new constitution or to institute expected reforms to permit greater public debate on government policy and ease repression against moderate opponents.

The constitution and political transition adopted in 1980 envisioned that Pinochet would remain as president until 1989 and possibly until 1997. Meanwhile, the "economic and social basis" was to be laid for a so-called "protected" democracy that would exclude communism and other ideologies opposed by the military.

"The problem is not the exact timing of the measures," said one leading Pinochet ally who helped draft the constitution. "It is that there is doubt that the willingness to carry through the transition exists."

In one serious critique, Jaime Guzman, one of Pinochet's apparent unwillingness to loosen his authoritarian powers, political analysts here now maintain that Pinochet might have to give some ground. If not, an opposition leader predicted, he may "find himself losing control in a way that will be hard to reverse."