Nigerian security forces continue combing for suspected hideouts for kidnappers of two German construction workers in Port Harcourt, the hub of the country's oil industry. Militants and criminals seeking ransom have attacked and kidnapped foreign workers in the Niger Delta, a vast wetlands which has all Nigeria's oil. Gilbert da Costa in Abuja has more in this report for VOA.

Two construction engineers employed by a German construction firm were abducted Friday from a construction site in the Niger Delta, some 19 kilometers from Port Harcourt.

No group has claimed responsibility for the incident, the latest to rock oil-rich Niger Delta in recent months. The region has seen numerous kidnappings targeting foreign firms in the past two years.

Some of the militants responsible demand a greater share of the oil wealth for the region's inhabitants, while others carry out attacks for ransom or political reasons.

Pessimism about insecurity in the Niger Delta is shared by President Umaru Yar'Adua who blames criminal elements for the crisis.

"Beside the political issues, I think there is one issue that we are missing out. It is the criminality and that we cannot run away from. Whether we sort out these political issues or not, as long as there are militant camps in the creeks and as long as there is a cartel that is carrying out bunkering of crude petroleum in the Niger Delta region, you can never have peace in the area. Because people make a lot of money from bunkering," he said.

Julius Berger, which is the biggest construction company in Nigeria, says it may pull out of the Niger Delta because of the deteriorating security situation there. The company is handling key infrastructural projects in the oil-producing region and a decision to suspend operations could be a setback for the government's drive to bring much-needed development to the delta.

Several foreign firms, including French tire company Michelin and oil servicing firm Wilbros, have left the Niger Delta because of security problems.

Figures released by the Organization of Petroleum Exporting Countries, OPEC, indicate that the unrest has reduced Nigeria's oil output by a quarter, causing it to lose its position as Africa's biggest oil producer to Angola, since April.