Shanghai authorities raised the death toll from Monday's apartment block blaze to 58 yesterday after DNA tests identified five more victims, and issued the first official count of those who remain missing following the disaster - 56. The news came as police said four more people were detained in connection with the fire, bringing the total to 12, and confirmed for the first time that managers of a building contractor suspected to have dubious links to local government were among those detained. Two 'responsible persons' at Shanghai Jiayi Building Decoration Engineering - the subcontractor responsible for the renovation project that caused the fire - were among the original eight detainees, police said. The four taken in for questioning yesterday were from three other firms linked to the project: Jingan District Construction, Jingan District Construction Engineering Supervision and Shanghai Dimu Property Management. Police refused to give any further details of those detained. A cloud of suspicion hangs over the Jingan district government over its links to Shanghai Jiayi and other contractors implicated in the investigation into the blaze. Shanghai Jiayi is listed as a state-owned entity under the umbrella of the Jingan district government. The two construction firms named yesterday also appear to be linked to that government. The district government declined to clarify the nature of its relationship with Shanghai Jiayi. 'The matter is currently under investigation and a full account will be made public once that work is complete,' a district government spokeswoman said. Mainland media labelled the government's relationship with the contractor abnormal, highlighting that Shanghai Jiayi won 35 of the 36 contracts it tendered for over the past three years, despite being cited by municipal government agencies for lax application of work and fire safety regulations on several occasions. Investigators of Monday's fire criticised the renovation work as being rife with 'illegal subcontracting' and flouting of safety measures. Workers were retrofitting polyurethane insulation foam to the outside of the tower when the fire broke out, part of a pilot environmental scheme to improve energy efficiency in the district. Although the district government was unable to provide details of the cost of the project or how many other buildings were fitted with similar insulation, a spokeswoman admitted the project had run since 2008. The two towers next to the one that burned down were also in the middle of renovations, and remain wrapped in scaffolding, the insulation visible through gaps in green plastic mesh. Investigators said the fire was accidentally set off by two unlicensed welders who then fled the scene. The insulation, along with flammable plastic netting and bamboo wicker on the scaffolding surrounding the building, were 'one of the main reasons' for the speed with which the fire spread, engulfing the entire building in minutes. The apartment block's burned-out shell continued to draw spectators yesterday afternoon, as a growing mountain of flowers and funeral wreaths built up on the street outside. But there was a mounting sense of anger at what many saw as government complicity in the disaster. 'It is all down to corruption,' said one retiree. 'There were just too many problems involved in whatever they were doing. If there were no problems, how would the building have burned down like that?'