Manila: A fire at a factory making rubber slippers killed 31 workers in the Philippine capital on Wednesday, and dozens were missing and feared dead, government and fire officials said. 

Rex Gatchalian, mayor of the northern Manila industrial suburb of Valenzuela, said firemen took four hours to get the blaze under control, and entered the burnt-out building to find an undetermined number of bodies.

They were unable to count the dead inside, but found no survivors, he said.

‘None of those trapped inside survived,’ Gatchalian announced to wailing relatives outside the factory.

He added that firemen could not immediately determine how many bodies had been inside, but relatives told officials up to 63 of their kin working in the factory at the time were unaccounted for.

Gatchalian urged the relatives to check again whether the missing kin were among those who had managed to escape the blaze.

‘I'm not saying all (the missing) are dead. We're still hoping they were able to jump out,’ he added.

The fire broke out shortly before noon (0400 GMT), apparently due to a spark from a welding job at the building's main entrance hitting flammable chemicals stored there, Gatchalian told ABS-CBN television in a separate interview.

He said the bodies of three other victims were earlier recovered.

Factory worker Nedy Neverio, 35, was among the distraught relatives who gathered outside the two-storey factory awaiting word on her elder sister Nora Verenzuela, 42, and two nephews, who are among the missing.

‘Someone told us no one escaped from the area where she was assigned’ packing slippers into bags, Neverio told AFP. 

‘My sister's workplace was near the chemicals. She was not able to get out because the flames had spread,’ Neverio added.

Injured survivor Emma Santa Agata told ABS-CBN many of her fellow workers were trapped at their work stations on the second floor of the building.

‘My boss and I were running out when we were blocked by fire and smoke,’ Santa Agata said.

‘There was a sudden explosion and he got hit on the arm,’ said the woman, whose hair was singed according to the network.