Nigerian President Olusegun Obasanjo has vowed to stamp out violence in the country's troubled Niger Delta. He spoke late Monday at a meeting with four foreign oil workers released by militants just hours earlier.

The Nigerian leader says his administration will not be intimidated by attacks on oil companies. He says new security measures will be introduced to stem rising violence in the area.

"I want to assure you and assure your employers, Nigerians and the international community, that we will do everything humanly possible to try to prevent a re-occurrence of what has happened," he said.

President Obasanjo also had a word for his country's independent media.

"I want to appeal to the Nigeria press, because we have some form of sensationalism in this. Now, if you glorify people who have done bad things, you're not doing any credit to your country or to yourself," said Mr. Obasanjo. "In fact, you're undermining the security of your country. I was told when I was in Davos, while we are working to get the people out, one paper came out with another sensation that another four had been kidnapped, which is a lie, which is untrue, and which can create both internally and externally the feeling of insecurity in the country."

Nigeria's largest labor organization, the Nigeria Labor Congress, which represents the interest of oil workers, has also welcomed the release of the oil workers. NLC Secretary General George Odah says improving security for oil workers should be a priority.

"It's understandable that our members are apprehensive about working in this area. Because if we are going to continue to have a situation where we're being threatened with the possibility of abduction at the slightest opportunity, this can't provide the necessary enabling environment to do work," said Odah. "The security of lives and property should be a primary consideration for both oil companies and respective government agencies that are charged with this responsibility."

None of the four former captives - a Briton, Bulgarian, Honduran and American - was allowed to speak to reporters. The release of the four has been warmly welcomed by most Nigerians. The U.S. embassy in Abuja has also welcomed their release. In a statement Monday it deplored acts of hostage taking and appealed for a solution to the problems in the Niger Delta.