SHANGHAI >> A deadly fire in a Shanghai high-rise apartment undergoing energy-saving renovations has spurred safety reviews of similar projects, as Beijing suspended such work in the capital.

Authorities said Friday that 58 were confirmed dead in the blaze, which swept through the 28-story building Monday after sparks from welding equipment set nylon construction netting and bamboo scaffolding alight, as flames spread throughout the building.

Most bodies were found where the victims perished inside their own homes, overcome by smoke, toxic fumes and heat, the city government said. Another 71 were injured, with an unknown number of people still unaccounted for.

The disaster has raised alarm over widespread efforts to meet energy efficiency targets by adding insulation to the outside of existing buildings — the project the welders were working on when the fire broke out.

Although the insulation meant for such work is supposed to be treated with fire retardant, it is nonetheless flammable. Many are now questioning if the energy savings are worth the risk.

Beijing, China’s capital, ordered projects similar to the one struck by the fire stopped, pending reviews and “rectification” of any problems.

But it is unclear if other cities will follow suit.

In Shanghai, a city of 20 million that has 15,000 high-rise buildings, construction projects were halted for two hours Friday for safety checks.

But officials in Shanghai’s downtown Jing’an district, whose local government was carrying out the renovations that caught fire, said such projects would continue.

China’s work safety chief blamed the fire on illegal contracting, unsafe materials and poorly supervised, unqualified workers.

Anguished family members and others angry over the government’s handling of the disaster are demanding answers.

“The government owes us a reasonable explanation and serious investigation. They have already lost the chance to apologize to those who were killed,” said Wang Lianguo, a neighbor who said he spotted the fire while doing laundry.

Police have detained eight suspects, including four they said were welders working without proper qualifications.

China has been tightening its energy standards, partly to meet its pledges on climate change and also to reduce waste and curb soaring consumption of costly and scarce energy resources.

One key aim is improving building energy efficiency. A large share of the country’s 141 billion square feet (43 billion square meters) of existing buildings are supposed to install insulation and other energy-saving features.

While the government is imposing relatively strict energy efficiency standards for new construction, less than 10 percent of existing buildings meet general, local building codes.

China is offering subsidies of 45-55 yuan ($7-$8.50) per square meter to encourage retrofitting of 150 million square meters of residential buildings by the end of this year. Overall, the market for such improvements is $600 billion, according to an estimate by the Beijing-based Energy Foundation.

But safety and other issues apparently are being overlooked as local officials and businesses rush to jump on the energy-saving bandwagon with retrofitting projects that, inevitably, are fresh opportunities for the corruption and corner-cutting endemic to construction work in this building-crazed country.

Monday’s fire, and a similar one triggered by fireworks that destroyed a luxury hotel at the Beijing headquarters for CCTV, China’s main television network, show the need for tighter controls on the use of new energy efficient materials, experts say.

Residents of the building destroyed in the fire said the district government had enticed those living there with promises of savings on their electricity bills.

The improvements were also meant to help raise property values, in an already pricey part of town.

Unsafe construction work is a huge headache for China, and residents of the destroyed Shanghai building complained that workers, lacking qualifications and working illegally for unlicensed subcontractors, were smoking on the job and leaving flammable materials piled up on the scaffolding.