LIMA, PERU, JULY 28 -- Alberto Fujimori took office as Peru's new president today, promising an all-out campaign against the corruption that pervades Peruvian society but offering few clues as to how he will attack the economic catastrophe that besets the country.

Fujimori, a bespectacled academic who six months ago was a political unknown, used much of his lengthy inaugural address to describe the broken, chaotic nation that outgoing president Alan Garcia leaves behind -- a country overrun by hyperinflation, severe recession, mounting political violence and worsening poverty.

"We must confront the gravest crisis in Peru's history," Fujimori said. "We inherit a disaster."

The new president gave only general outlines of how he will seek to solve the economic crisis, pledging a balanced approach that recognizes there are no "magic recipes." The one specific measure he announced was a request that Peru's legislature give him six months' authority to set tax policy by decree. Other officials said a full economic rescue package might not be ready until the middle of next month.

Fujimori's first address to the nation as president concentrated heavily on his promise to bring honesty to a government riddled with corruption. "Our administration will be implacable," he said, promising to appoint an anti-corruption czar. "The state will cease to be the place where great fortunes are amassed through power."

To many political leaders, Fujimori remains an unknown. Associates say he is loath to delegate authority, and although he listens to a range of advice, he appears to rely mainly on the counsel of his close-knit family and a few trusted aides when making decisions.

In a day of ornate ceremony, the most dramatic moment came when Garcia rose to deliver a farewell speech to the legislature. As soon as he began speaking, conservative legislators set up a racket that drowned him out. After 10 minutes of pounding their desks and hooting every time Garcia opened his mouth, the conservatives finally walked out.

Also sworn in today was a coalition cabinet whose eclectic makeup is as surprising as Fujimori's spectacular political rise. By far the most pressing issue Peru's new leaders confront is the economic situation.

Inflation reached 2,775 percent last year, while real incomes fell by more than 20 percent and the overall economy shrank by 12 percent. Fujimori said today that only 15 percent of the work force is fully employed, with 10 percent having no work at all and 75 percent only marginally employed. The government's cash reserves are essentially exhausted.

With inflation now being calculated daily -- prices rose by 6 percent on Thursday alone, according to one research firm -- and the government in such straits that checks to public workers are bouncing, Fujimori has not explicitly abandoned his promise not to jolt the economy with a harsh adjustment program.

But there are some signs that Fujimori is looking for a way out of his populist pledge. He has bettered his relations with the conservative business community, and today he reiterated his intention to return Peru to the good graces of international lenders, which almost certainly will require tough anti-inflation measures.

Fujimori's clearest signal that he may be reversing his pledge was the announcement last week that Juan Carlos Hurtado Miller will be prime minister and minister of the economy, posts from which he will direct Fujimori's attempts to cure the ailing economy.

Hurtado Miller served as agriculture minister under former president Fernando Belaunde Terry, whose conservative Popular Action party supported Fujimori's opponent in the presidential campaign, novelist Mario Vargas Llosa. The appointment was hailed by conservatives and the business community, but the left viewed it with caution.

Fujimori's other cabinet appointments fit no real pattern except that virtually all were to some extent unexpected.

Gloria Helfer, the new minister of education, belongs to a socialist faction of the United Left coalition. The new agriculture minister, Carlos Amat y Leon, ran for vice president under the banner of a group of parties known as the Socialist Left. The new minister of the interior, Adolfo Alvarado Fournier, is an active-duty army general. The new minister of industry, Guido Pennano, is an economist who has been critical of both the left and the right.

"The cabinet is characterized by being made up of high-level professionals . . . of various parties," Fujimori said in announcing his choices. The one major force notably absent from the new administration is Garcia's party, the American Popular Revolutionary Alliance, widely blamed for the country's economic collapse.

Fujimori, who turned 52 today, is the former president of the National Agrarian University and has never held elective office. He stunned the political establishment here by finishing a close second to Vargas Llosa in the first round of presidential balloting last April and then swamping the novelist in a June 10 runoff.

The son of Japanese immigrants, Fujimori capitalized on the anger and frustration Peruvians feel about the failings of traditional politicians and parties, and on widespread fear of the austere economic reforms that Vargas Llosa promised to impose. On another level, he became the champion of Peru's poor, brown-skinned majority and painted Vargas Llosa as a stalking horse for the white elite.

He now faces the challenge of governing without the backing of a coherent political party. His Change 90 coalition of small businessmen, technocrats and evangelical Christians has nothing close to working majorities and will have to make alliances with either the left or the right to get Fujimori's legislative program approved.

Change 90 displayed its lack of experience and savvy again Wednesday when, largely because of internal wrangling, it failed to meet a deadline to submit a slate of candidates for leadership positions in the legislature's lower house.

After much political wrangling, the deadline was waived, and now Change 90 legislators will hold the top posts in both the Senate and the Chamber of Deputies.