Workmen with wrecking balls and bulldozers attacked rubble heaps in Mexico City's most devastated neighborhoods today and the country's private industry group appealed for a year-long suspension of interest payments on the Mexican debt.

The demolition crews at work and the business concern over Mexico's financial health illustrated a shift in emphasis here from immediate rescue efforts to longer-term recovery from last Thursday's earthquake.

Mexican and foreign teams persevered in searching for survivors and pulling bodies from the debris, driven by hope of finding still more living victims under the piles of concrete and steel ruins. A half-dozen survivors were reported to have been discovered yesterday and specially trained dogs from Europe and the United States continued today to sniff through the wreckage.

Meanwhile, wrecking crews started clearing operations on collapsed buildings where all hope of finding survivors has evaporated and all known corpses have been recovered, officials said.

Authorities must now decide when those wrecking crews should move on to buildings where there was, at one point, some hope of survivors. It is feared that demolition work could kill anyone remaining alive in the ruins of the buildings. At least 7,000 buildings were damaged in Thursday's earthquake and a second large aftershock that struck Friday, according to insurance inspectors.

Government officials said about 250 of these collapsed totally. Scores more were so damaged that they will have to be demolished before they fall. Government and foreign experts, including a U.S. team, have been surveying the city to decide which to destroy, either by wrecking ball or by carefully wired explosions.

A number of damaged buildings housed government ministries and other offices. President Miguel de La Madrid's government ordered the hardest-hit agencies to seek temporary quarters outside the capital to keep working while the city is cleaned up.

The Education Ministry announced that some classes will resume Wednesday. Many pupils will be unable to attend, however, because 152 of the capital's 4,000 schools were badly damaged, according to a ministry count, and others are being used to shelter homeless families.

Dante Gomez of the Unified Socialist Party, the opposition communist organization, said the party's members of Congress plan to demand an investigation into allegations that some buildings collapsed because of faulty construction. His declaration reflected widespread speculation that corruption allowed some builders to skimp on cement or steel reinforcement in a number of structures that collapsed, particularly those built for the government.

Mayor Ramon Aguirre, in apparent response to these reports, said authorities will investigate why some buildings collapsed and others nearby did not.

Interior Minister Manuel Bartlett, pursuing an apparent government effort to minimize the scope of the disaster, announced that de la Madrid has no plans to declare a state of emergency. Only scattered looting has been reported and armed soldiers have cordoned off neighborhoods that suffered the most damage, officials pointed out.

In the same vein, the Health Ministry disputed reports that decaying bodies have created health hazards.

The United States, other countries and international aid agencies have offered extensive assistance to help Mexico deal with earthquake damage. But analysts here noted that financing to meet the country's burdensome debt-servicing requirements is the key to recovery.

The National Chamber of Industry and Transformation, the country's main industrial association, called for a 12-month postponement of debt servicing to ease the reconstruction period. The call, from chamber President Carlos Mireles Garcia, marked a departure for Mexico's business leadership, which in the past has urged the government to repay on schedule.

The moratorium would amount to savings of about $900 million a month, the estimated cost of interest on Mexico's $96 billion in foreign debt. De La Madrid's government has announced no such request.