PORT HARCOURT, Nigeria April 14 (Xinhua) -- The police in oil rich Nigeria Rivers State on Wednesday confirmed the release of four foreign nationals abducted by gunmen operating in the region.

State police spokesperson Rita Abbey confirmed this to Xinhua on phone.

"Yes, the kidnapped expatriates were released on April 12," she said.

On if any ransom was paid, Abbey said the police was not aware of that.

The expatriates, three Syrian and one Lebanese were taken hostage on April 9. One police officer was killed in the process.

The Niger Delta is an unstable area where inter-ethnic clashes are commonplace. Access to oil revenue is the trigger for the violence.

Over 300 foreigners have been seized in the Niger Delta since 2006. Almost all have been released unharmed after paying a ransom.