The agreement securing the release of the more than 250 captives — which include 35 Britons, 17 Americans and two Canadians — was reached Friday between owners of the four oil rigs and negotiators for the Nigerian hostage-takers, said the secretary general of Nigeria's biggest oil workers union, Joseph Akinlaja, who aided in the negotiations.
"Any moment from now, all those on the rigs will leave," Akinlaja told The Associated Press by phone from the Nigerian capital, Abuja, where the negotiations were held.
Peter Akpatason, another Nigerian labor official, confirmed that an agreement was reached. "The dispute has been resolved," he said.
Guy Cantwell, a spokesman for the Houston-based owner of the rigs, Transocean Inc., also said that he understood the hostages would leave the offshore oil platforms, where they've been held since April 19 by about 100 disgruntled Nigerian workers.
"We understand the meeting has ended and an agreement has been reached. We understand a communique is being prepared to ensure everyone on the rig will leave," Cantwell said by telephone from Houston.
Details of when and how the hostages will leave the oil installations were being arranged, Akinlaja said.
The rigs, about 20 miles off Nigeria's coast, are drilling wells run on behalf of multinationals Royal/Dutch Shell and TotalFinaElf.
Sabotage and hostage-takings by community activists, labor groups and thugs demanding compensation for land use and alleged environmental damage are relatively common in the southern Niger Delta, where nearly all of Nigeria's oil is drilled.
Nigeria is one of the world's largest oil exporters and the fifth largest producer of U.S. oil imports.
Transocean announced April 22 that a strike had begun but did not mention captive workers. Other oil companies in the past have preferred to deal with such crises out of the glare of media coverage.
The strikers are protesting a decision by Transocean to use boats instead of helicopters to ferry them from company rigs about 25 miles offshore the restive Niger Delta state of Rivers, said Joseph Akinlaja, secretary-general of Nigeria's largest oil workers' union.
The strikers were also angered by company threats to discipline five union members, said Akinlaja, adding that his union is not supporting the strike.
A U.S. source told CBS News a handful of workers had been dismissed for "fiscal malfeasance."
Thirty-four people were allowed to leave two rigs by boat Monday, according to Cantwell. Two were Transocean employees, while the others work for third-party service companies.