(CNN) -- The Democratic Republic of the Congo declared two days of mourning Monday and Tuesday for the victims of the massive oil tanker explosion that killed more than 230 people over the weekend.

The toll from the explosion in the central African nation rose to 232 on Sunday, up two from earlier reports, government spokesman Mende Omalanga said.

President Joseph Kabila's declaration of a day of mourning requires flags to be lowered around the country and at Congo's embassies worldwide, Omalanga said.

The oil tanker blew up Saturday in the southern city of Sange, near the country's border with Burundi, after it overturned while passing a bus, Omalanga said.

Most of the victims had been sitting in a bar near the accident site watching the World Cup match between the Netherlands and Brazil, he said.

When fuel began to spill from the overturned tanker, local residents attempted to collect it -- but one was smoking a cigarette, causing the tanker to explode.

CNN's Mitra Mobasherat contributed to this report.