By Anna Borzello
BBC News, Port Harcourt
Eight communities in Nigeria's southern Niger Delta have gone to court to force the government to stop gas flaring.
Activists argue that gas flares create acid rain
Activists argue that flaring damages the environment and is also illegal. The government has promised to phase it out by 2008.
Nigeria flares the most gas in the world. Campaigners say it creates more greenhouse gas emissions than all other sources in Sub-Saharan Africa combined.
The country is the largest producer of crude oil on the continent.
But most of the associated wealth has been squandered or stolen.
More than 60% of the population now live in poverty.
Nigeria's oil-producing Delta region is lit by high plumes of orange flame, often accompanied by dense black smoke.
Action co-ordinator Environmental Rights Action (Era) says flaring causes health problems, reduces crop yields and creates acid rain which eats away at the corrugated-iron roofs in the area.
The Delta region holds the bulk of Nigeria's oil reserves
The government, which works in partnership with the five oil majors - Shell, Exxon Mobil, ChevronTexaco, Agip and TotalFinaElf - has vowed to phase out flaring by 2008.
However, the process has been slower than anticipated - with at least one company, Shell, pushing back their projected completion date.
Era argues that flaring has been illegal in Nigeria since 1984.
The group wants the courts to force the oil companies to shut down their sites until they have put in place facilities to deal with the gas.
This is unlikely to happen as crude oil accounts for over 90% of Nigeria's export earnings.
But the group hopes that a ruling in their favour will open the way for communities to claim compensation.