US officials Tuesday expanded a fishing ban in the Gulf of Mexico by more than 8,000 square miles (20,000 square kilometers) amid a spreading oil slick.
Some 54,096 square miles (140,000 square kilometers) of Gulf of Mexico waters are now closed to fishing, the National Oceanic and Atmospheric Administration (NOAA) said. That area is close to the size of Greece, according to an AFP calculation.
"Closing fishing in these areas is a precautionary measure to ensure that seafood from the Gulf will remain safe for consumers," the agency said in a statement.
Some 77 percent of the Gulf of Mexico remained open, it added, despite a ruptured oil well which has been leaking into the waters since an explosion on April 20.
Exactly how much oil has spilled into the Gulf is not yet unknown, but BP which leased the Deepwater Horizon rig had initially said some 210,000 gallons, or 5,000 barrels, were spewing into the sea every day.
In the past week however, BP has managed to siphon hundreds of barrels a daily to the surface via an insertion pipe placed into the ruptured pipe.
The agency was also working with the Federal Drug Administration to start a seafood sampling plan, to test seafood from inside and outside the closure area, as the expanded fishing ban went into effect at 5:00 pm local time (2200 GMT).
Commercial fishermen in the Gulf harvested more than one billion pounds of fish and shellfish in 2008.
Explore further: More of Gulf closed to fishing because of spill