Two oil unions have called an emergency meeting after the kidnappings of 17 workers, mostly foreigners, in the last month. Oil companies have imposed strict travel restrictions on their staff to try to keep them safe.
Government attempts to rescue a Nigerian hostage in the delta ended in a shoot-out on Sunday. Up to 10 members of the Movement for the Emancipation of the Niger Delta were killed and it is still unclear whether the hostage, an employee of Royal Dutch Shell, survived.
"We are afraid for the safety of our members and anyone working in the Niger Delta. We feel the government is not doing enough," said Peter Esele, president of the Petroleum and Natural Gas Senior Staff Association of Nigeria.
Esele said the decision-making councils of the association and its ally, the blue-collar National Union of Petroleum and Natural Gas Workers, would vote on August 30 on whether to call on their members to leave the region.
Last week Olusegun Obasanjo, the Nigerian president, ordered the military to meet the militants with "force for force".
"This does not in any way solve the problem," Esele said, arguing that there was no military solution to the situation and that a military crackdown risked further endangering the lives of workers.
The oil-rich Niger delta provides
much of Nigeria's wealth
Esele accused Nigerian authorities of making greater efforts to release foreign hostages than Nigerians.
"The Nigerian government doesn't have as much respect for its own citizens. If foreigners are involved the government does everything it can to get them out but if it's a Nigerian there is neglect," he said.
The violence stems from widespread resentment by locals that their region provides the bulk of Nigeria's wealth while they have received few benefits.
Organised gangs now also kidnap for ransom and battle to control a lucrative trade in stolen crude oil.