RIO DE JANEIRO — The Brazilian Navy said on Friday evening it had begun an operation to sink the decommissioned aircraft carrier São Paulo, packed with an undetermined amount of asbestos and other toxic materials, about 220 miles off the country’s northeastern coast.
A navy news release did not give details of the operation, and it was not clear whether the ship had gone down. Naval officials did not immediately respond to requests for comment.
The carrier had spent months at sea, refused permission to dock back in Brazil after plans to recycle the ship in Turkey collapsed. Environmental groups accused Brazilian officials and the company that owned the ship of underreporting the amount of hazardous material aboard. Under pressure from environmental groups, Turkey canceled permission for São Paulo to dock after the ship and its tug had already reached Gibraltar.
The vessel, by then in need of maintenance, was forced to head back to Brazil, where it was apparently refused permission to dock by civilian officials. The navy, for unexplained reasons, also refused to offer its bases. So the ship spent months being towed in circles as its condition deteriorated.
A navy news release this week warned of “deteriorating hull buoyancy conditions and the inevitability of spontaneous/uncontrolled sinking.”
Officials had said earlier that the 30,000-ton carrier would be sunk off Pernambuco State at a spot about 3,000 miles deep, outside any environmentally protected zones or areas with undersea cables.
In the last decade, according to the Shipbreaking Platform, a watchdog organization that advocates for sustainable recycling, Brazilian companies have disposed of more than 50 vessels in South Asia, where regulations for handling toxic materials are lax.
“Several of these vessels were exported from Brazilian ports without following the international rules on trans-boundary movements of hazardous waste,” said Nicola Mulinaris, a policy advisor at Shipbreaking Platform.
The plan to recycle São Paulo in Turkey was thought to be Brazil’s first attempt to scrap a ship under well-regulated conditions.
The toxic material aboard São Paulo could disrupt ecosystems, kill animals and plants and poison marine food chains with heavy metals, according to IBAMA, Brazil’s environmental agency.
Rosângela Muniz, the interim director of IBAMA’s environmental quality department, said the agency had asked the navy for information, including the method that would be used to sink the ship, so it could help mitigate the impact. There had been no response by the end of business on Friday.
Ms. Muniz said her team was frustrated that the effort to recycle São Paulo sustainably had failed.
“This ship is an environmental liability that has only one correct destination: recycling,” she said. “We know there will be other requests like this one that will get to IBAMA, and we hope they will have an outcome that is better for the environment.”