Nigeria's largest coalition of labor organizations, the Nigeria Labor Congress is calling for the immediate release of four foreign oil workers. The call comes against the backdrop of increased tension following Tuesday's attack on the offices of an Italian oil company.

The Nigeria Labor Congress on Wednesday issued an appeal for the release of four oil workers being held by militants in the troubled Niger Delta.

The NLC enjoys tremendous goodwill even within the ranks of those opposed to the government. NLC Secretary General George Odah says the capture of foreign oil workers will not help the cause of the militants.

"The position of the Nigeria Labor Congress is that hostage taking is not a solution to the crisis and we therefore have appealed passionately to the group that might be holding the four oil workers to release them," he said.

As the crisis enters its second week, leading opponents of the government are equally voicing their concern. A member of the Nigerian opposition, Maxi Okwu, says the use of what he described as terrorist methods in the delta is unacceptable.

"I understand the anger, the frustration in the Niger Delta area, particularly amongst the younger elements and indeed the entire community, a failure of governance, an obvious let-down by the Nigerian state to an area that could be described as the goose that lays the golden eggs for Nigeria," he said. "But that in no justifies terrorist tactics. There is an international zero tolerance for terrorism and the youths and the militants in that area ought to understand that they are destroying their case. They are destroying the goodwill they enjoy internationally and locally."

The appeals come hours after militants staged an attack on the offices of an Italian oil company in the southern city of Port Harcourt.

Witnesses say men dressed in military uniforms and carrying assault riffles stormed the offices of Agip. Eight policemen and an employee of the were killed in the gunfight. Several more were said to have been injured.

More Nigerian troops have been sent to the area since militants launched attacks on oil companies a few weeks ago.

Tuesday's attack was the latest in ongoing violence which has claimed more than 20 lives, cut oil production by 10 percent and pushed up crude oil prices on the international market.