The vehicles met head-on at around 6am, along a road in Alberga, just outside of Eskilstuna, roughly 100 kilometres west of Stockholm.
“According to the witnesses, the driver of the smaller vehicle came onto the wrong side of the road,” Jocke Andersson of the Sörmland police told the Expressen newspaper.
“The bigger vehicle had no possibility of swerving or slowing down,” Andersson added.
After the collision, the van immediately went up in flames, and emergency services arrived on the scene could not save the driver.
The driver of the tanker sustained minor injuries and has been taken to hospital in nearby Västerås.
The road, Highway 56, has been cordoned off and is expected to remain closed for several hours as the vehicles are removed and the road is cleared and cleaned.
Police estimated that it will be several hours before traffic can return to its usual flow.