The accident occurred at a coke plant near Luleå operated by Swedish steelmaker SSAB with rescue teams at first trying to find out whether the spillage of coal tar had trapped the missing workers.
"A massive amount of coal tar has leaked from a cistern out out into a ditch around the cistern. They've now been found dead in the ditch in the coal tar," emergency crew team leader Patrik Bylin told the Aftonbladet newspaper.
The two workers were subcontractors who were performing maintenance on a large cistern when the approximately 300 cubic metres of coal tar flowed into the ditch surrounding the tank, submerging the two men.
The accident was first reported at 12.20pm, but the men were not found until 2.30pm. Norrbotten police confirmed the men's deaths to the TT news agency.
"We've launched a preliminary investigation together with the Swedish Workplace Safety Agency (Arbetsmiljöverket) following the accident," SSAB spokesman Kent Isaksson told the TT news agency.
Police have also launched an investigation into a workplace safety violation.
The two men who died in the accident work for Infjärden värme AB (IVAB), based in Piteå.
"I don't want to comment right now," IVAB CEO Sune Westerberg told the local Norrländska Socialdemokraten (NSD) newspaper.
"What's happened is just too difficult."
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