Gunmen dressed in black balaclavas and camouflage flak jackets approach in a boat. As it draws alongside, their voices can be heard singing. The chorus fades and they introduce themselves.
"We are the security men of the Niger delta," says one of the men in the blue speedboat bristling with assault rifles and rocket-propelled grenade launchers. "Nobody is going to hurt you. We are everywhere in the Niger delta."
The singing militiamen are part of the newly organized Movement for the Emancipation of the Niger Delta (MEND) and are the latest expression of local resentment in a region of the country where tens of millions of dollars worth of oil are extracted each day, but most people live on only several hundred dollars each year.
The MEND organization, whose leadership remains a matter of speculation, appears to be better organized, trained, and equipped than any other group to emerge so far from this restive, swampy region.
"The way [the MEND militiamen] have been able to engage [the Nigerian military] in the last one month or so, the sophistication of firepower, it's not child's play," says Kayode Komolafe, managing editor of Nigeria's This Day newspaper. "What we have in this place is something aching. If we are not careful it could explode into greater warfare."
Nigeria is the world's eighth largest oil exporter and the fifth largest supplier of crude to the US. MEND's recent sabotage of pipelines and other oil facilities has so far shut off over a fifth of the country's oil output, steadily driving up world oil prices.
On Sunday, MEND threatened more attacks and vowed to cut daily oil exports by 1 million barrels this month, adding to concerns for Organization of Petroleum Exporting Countries (OPEC) as it prepares for a strategy meeting in this week.
MEND recently captured, and subsequently released, six hostages from the US, Egypt, the Philippines, and Thailand last week, but is still holding two Americans and a Briton. MEND has killed at least 14 soldiers in gun battles, but the Nigerian military has refrained from launching an offensive out of fear for the hostages' lives.
An e-mail statement from a MEND spokesman, who goes by the name Jomo Gbomo, said the hostages were "not in risk of death," but they could be held for a good while longer if the military fails to withdraw all troops from the delta - a condition unlikely to be met.
At last week's meeting with journalists in the middle of the Escravos River, a MEND gunman swore to "stop oil flowing from our land" until a host of political and economic grievances were resolved.
High up on the list of demands was the release of two ethnic Ijaw leaders: secessionist militia boss Mujahid Dokubo-Asari, who was arrested in September on treason charges, and Diepreye Alamieyeseigha, a former southern governor who jumped bail in Britain on money laundering charges and was jailed soon after arriving back in Nigeria.
MEND is also demanding that Royal Dutch Shell, which produces close to half Nigeria's oil, pay the Ijaws $1.5 billion in environmental compensation (as demanded by the country's legislature) and that the delta be given greater control over oil revenues.
At present, 13 percent of Nigerian oil revenues flow back to regional state governments, which are renowned for corruption. Delta politicians and militants are demanding that, at a minimum, the region receive 50 percent.
Abel Oshevire, spokesman for the regional Delta state government, says constitutional amendments allocating greater control of the region's resources to local authorities are needed. "We are working seriously at this and we should be able to achieve our desire."
Observers are taking MEND seriously. They militiamen boast of an arsenal including heavy M-16 guns and more serious weaponry than any other Nigerian militias to date. Their 400-horsepower boats are faster than Nigerian Navy craft.
For now, authorities say they don't knows where the arms are coming from, but observers suspect that they are purchased with the proceeds of a lucrative trade in stolen oil, known in Nigeria as "bunkering."
A source close to government teams working for the hostages' release points to the group's discipline and professional bearing as signs that its members have probably undergone months of serious training by experienced soldiers or former soldiers. Mr. Gbomo says the militia includes "dismissed, retired, and serving military personnel."
This militia's actions are also different from other similar groups in the region. Before MEND, kidnappings of foreigners had not been carried out to push for national political reforms, but rather were a means of extracting ransom payments or forcing oil companies to help a given local community.
President Olusegun Obasanjo insists that he is doing what he can for the delta's development, including setting up a development agency for the region. Locals say the agency's projects, which include road-building and a computer-training center, don't see a real difference.
Demieari Von Kemedi, a human rights campaigner in the oil city of Port Harcourt, says Mr. Obasanjo's strategy is to "create the impression that he is not too worried about the issues and, secondly, that the issue may not be as important as people represent it to be."
By putting local governors in charge of negotiation attempts, Mr. Von Kemedi says, Obasanjo is "giving the issue a local appearance rather than an issue of national importance ... and by so doing not creating any forum at all for many fundamental questions" to be discussed.