Warri (Nigeria): Security forces today detained four Americans and a Nigerian man accompanying them for illegally travelling by boat in southern Nigeria's restive oil-rich creeks, officials said.

The security forces pitted against militants in the vast wetland region consider much of the riverine Niger Delta a military zone and have barred outsiders from travelling there without express consent by authorities.

Nigerian Brig Gen Wuyep Rintip said the group was seized today for flouting the ban and were to be flown to the capital, Abuja. He did not identify the detainees. The US Embassy was not immediately available for comment.

Various foreigners have been picked up in the Niger Delta in recent months as security forces have stepped up efforts to quell unrest in the region.

Several foreigners, including two documentary filmmakers, were expelled from the country on alleged visa violations.

An American aid worker, long a resident in Nigeria, was arrested with the filmmakers was charged with spying. The charges were later dropped and she was released.

Nigeria, Africa's biggest oil producer, pumps its crude from the Niger Delta, which remains deeply impoverished despite the natural bounty. Armed groups roam the region of creeks and swamps, stealing crude oil for resale and engaging in other criminal activities.

Some gunmen also launch militant attacks seeking to pressure the government to release their leaders and send more government-controlled oil revenues to the anarchic area.

Source : PTI