Rescue workers today searched the smoldering rubble of a leveled working-class neighborhood in northeastern Mexico City for more victims of a massive gas-fed blaze that yesterday morning claimed at least 314 lives, according to the latest Red Cross estimate.

The official death toll is expected to rise as more bodies are found and as patients succumb in overcrowded hospital burn wards, Alejandro Barrios of the Mexican Red Cross said. By midday today, 17 deaths had been reported by area hospitals, while 297 charred corpses were removed from the disaster site yesterday, the Red Cross reported.

Other reports put the death toll at more than 500.

Mexican firefighters brought the blaze under control at 8 p.m. yesterday, about 14 hours after the conflagration was ignited by a series of spectacular explosions at the city's largest natural gas distribution facility, owned by Petroleos Mexicanos, the state oil monopoly.

The fire "was without doubt one of the greatest tragedies Mexico has suffered in recent times," President Miguel de la Madrid said in a televised address last night. "Mexico is in mourning today," the president said. He ordered an investigation into the cause of the blaze.

The disaster left an estimated 2,750 people seriously injured and forced the emergency evacuation of about 200,000 area residents.

It has prompted a renewed political debate about the presence of refineries, natural gas plants and other Petroleos Mexicanos facilities in densely populated districts of the capital. Environmentalists, backed publicly by some city officials, have repeatedly demanded the relocation of the installations, although more for air quality than safety reasons. Federal authorities have endorsed such industrial decentralization proposals in principle but contend that the removal of major plants would prove too costly for the debt-strapped government.

As death estimates from the gas explosions rose steadily yesterday afternoon, Alfredo del Mazo, governor of Mexico state, declared that it was "perhaps not prudent" to place such facilities in residential zones.

Yesterday's fire devastated the five-acre Petroleos Mexicanos gas distribution center and raced quickly through a 20-block section of San Juan Ixhuatepec, a low-income housing tract adjacent to the gas depot. Most of the victims were incinerated in the first minutes of the blaze, according to firemen, and little but blackened cinder-block shells now remains of their homes.

Several 50-foot-long cylindrical propane storage tanks were propelled skyward in the blast, one of them crushing the house on which it landed nearly a half-mile away. Giant steel shards from four fire-ravaged spherical tanks could be seen imbedded in the grounds surrounding the gas plant's wreckage. A sulphurous mist lingered above the site, while gas leaks from ruptured tanks were flared off to minimize the risk of further explosions.

Spokesmen for Petroleos Mexicanos said the firm was still unable to quantify the damage to the plant, estimated to have supplied cooking and heating gas to as many as half of the metropolitan area's 17 million residents. Propane will now be delivered from distribution centers north of the city until "entirely new facilities" are built in an emergency construction program, Energy Minister Francisco Labastida Ochoa said today.

Petroleos Mexicanos officials first placed the blame for the blast on a gas delivery truck said to have exploded in the loading yard of Unigas, a private gas distribution company located next to the Petroleos Mexicanos supply center. This explanation was later withdrawn, with the monopoly stating in a press bulletin last night that the origin of the blaze remains "unknown." Employes answering the telephone at Unigas headquarters said no authorized company spokesmen were available for comment.

In the past three years, scores of deaths have been attributed to Petroleos Mexicanos gas explosions and pipeline accidents elsewhere in the country, but yesterday's blast was the first such incident to occur in Mexico City. Petroleos Mexicanos, better known as Pemex, its commercial acronym, asserted last night that the fire appeared to have been ignited outside the gas supply center, reaching the Pemex facilties through a gas pipeline and detonating its pressurized storage tanks. The fire destroyed the Pemex plant, but left the neighboring commercial gas installations virtually unscathed.

"We were incredibly lucky," a fireman said today, gesturing at the rows of intact gas tanks standing several hundred yards from the charred ruins of the Pemex plant.

Pemex's own specialized firefighters helped keep the blaze from threatening a nearby network of major oil and gas pipelines, averting what authorities acknowledge could have been a still greater disaster.

The 314 fatalities reported today make yesterday's blaze the worst fire in the country's history and the most serious single disaster recorded in the capital city this century. Today, as thousands of city residents gathered in the central square to commemorate the 74th anniversary of the Mexican revolution, President de la Madrid asked the crowd to pause for a moment of silence.

Pemex officials reported tonight that five plant employes died in the blast, which they said consumed 80,000 barrels of gas.

Thousands of families remain lodged in emergency shelters in schools and churches, although most of the evacuated areas were untouched by the fire. "There is probably no longer any risk of further explosions, but we have to be very sure before we bring people back in," Capt. Jesus Buentello, chief security officer for Mexico state, said today.

Several prominent government-aligned politicians today voiced support for the removal of Pemex oil and gas installations, including the large Azcapotzalco refinery, located in the heart of one of northern Mexico City's most heavily populated districts.

Few informed observers, however, expect the government to enforce such a ban on hazardous and polluting industries in Mexico City, where half the country's industrial infrastructure is now concentrated. Marcelo Javelly, minister of ecology and urban development, recently suggested publicly that Mexico "can't afford clean industry." The capital city must choose between dirty industry and "no industry," Javelly said.