LAGOS, Nigeria (CNN) -- Nigerians took to the streets of the country's commercial capital on Monday to protest against an increase in fuel prices that have more than doubled in the past week.

Protesters lit bonfires from used car tires on the outskirts of the city of about eight million, and forced commuters out of commercial vehicles, according to witnesses.

"We are protesting the increase in fuel prices because there is just no way we could survive under it," said one of the protesters, who shouted slogans against the military government of Gen. Abdulsalami Abubakar.

The price increase is the result of the government deregulating the marketing and distribution of petroleum products. The government has said it can no longer afford the subsidies.

Gen. Abdulsalami Abubakar

The protests came as the authorities in the oil-rich southern region of Bayelsa lifted a state of emergency imposed last week during clashes that left at least 20 people dead in the Niger delta region.

Those clashes came against the background of an ultimatum issued by several ethnic Ijaw communities in that region. The Ijaw called for international oil companies to quit their operations in the Niger delta territory until the issue of "ownership and control of the vast oil deposits is determined." The ultimatum expired on December 30.

But over the weekend, a temporary peace agreement was worked between the Ijaw community and government troops protecting oil installations in the state.

A spokesman for the military administrator of Bayelsa state said the dusk-to-dawn curfew would no longer apply but that a ban on public demonstrations remained in place.

"Anyone or group that wants to take part in any of them must seek police clearance," said spokesman Norman Morris.

Although Nigeria is the world's sixth-largest oil-producing nation, few people in the oil-rich Niger delta benefit from its wealth. Many towns exist in abject poverty without electricity, clean water or medical clinics.

Ethnic groups have for years protested the government's mismanagement of the oil industry and have demanded greater compensation for the use of their land.

Gen. Abubakar's military government increased troop strength in the region over the weekend to quell the disturbances, which threatened the revenue base of the country in the countdown to the restoration of civilian rule next May, when Abubakar is expected to hand over power to a civilian administration.

The Associated Press and Reuters contributed to this report.