Rio de Janeiro state's top environmental official has acknowledged that the Olympic pledge of slashing the levels of pollution flowing into the trash- and raw sewage-filled Guanabara Bay by 80 percent is unattainable by next year's summer games.

Andre Correa said he couldn't provide an estimate of how much officials would actually succeed in cutting the flow of pollutants into the bay, where the Olympic sailing and wind surfing completions are to be held.

He told reporters at a news conference Friday he wasn't sure whether Olympic officials had yet been warned.

Environmentalists have been warning of negligible progress in the cleanup efforts for year. Sailors' associations have also expressed reservations about water quality in the bay and voiced concerns that it could make athletes sick.