The illegal dumping of untreated waste in Nigeria's restive Niger Delta has infuriated the local community, which is demanding quick government intervention. The southern oil-rich region is considered one of the most polluted locations in the world.

Police spokesman Charles Nwuka says an oil servicing company was being investigated over the dumping of sewage in Emu-Umo, a village with a population of about 8,000 in Delta state, western Niger Delta.

"There was something like that at Ume-Umo," he said. "National Oil Spill Detection and Response Agency, based in Warri, carried out an investigation into it. And it was discovered that it is not actually toxic waste but effluent water."

The chief concern among the villagers is the proximity of the suspected toxic waste, which has turned into a foul-smelling sludge, to their source of drinking water. Village head Emmanuel Ebie told VOA that the dumping of untreated sewage a few weeks ago has created enormous difficulties for the community.

"The substance was dumped in mainly farm land area and some of our crops are affected, even drinking water in that area," he added. "People who reside in farm settlements in those areas, they no longer drink from hand-made wells in that place because they suspect most of the effluent must have gone into the water and the effect may be dangerous if they drink it. People are skeptical about going to farms in the area because they don't know what effect this thing can have on their body."

A girl dumps refuse near their house at the waterside area in Port Harcourt, Nigeria (File)

Experts say oil companies and auxiliary entities have been dumping millions of gallons of waste material into the creeks and waterways of the Niger Delta for decades.

And oil spills have compounded the damage to the Niger Delta's fragile mangrove forests. The Delta is home to 7,000 kilometers of Africa's remaining 9,000 kilometers of mangrove.

A study by a panel of independent experts in 2006 showed that about 1.5 million tons of oil had been spilt in the Niger Delta over the past 50 years. It said pollution had destroyed the livelihood of many of the 20 million people living there and contributed to the upsurge in violence.

The study concluded that the delta was now one of the five most polluted regions in the world.

The National Oil Spills Detection and Response Agency, a government agency responsible for oil pollution management in Nigeria, at the weekend criticized more than 60 oil companies for violating guidelines on oil spills management.

It accused the Nigerian oil industry of failing to report oil spills, clean up impacted sites and negotiate the payment of compensation to communities affected by the spills.

Nigeria, Africa's largest oil producer, has pumped more than $400 billion worth of crude from the southern delta states, since the 1970's.  But high unemployment in the delta, environmental degradation due to oil and gas extraction, and a lack of basic resources, such as fresh water and electricity, have angered some of the region's youth and incited them to take up arms.