Published: Aug 27, 2010 5:07 PM EDT
Updated: Aug 27, 2010 2:07 PM EDT

NEW ORLEANS (AP) - The U.S. is reopening more federal waters in the Gulf of Mexico for commercial and recreational fishing that had been closed because of the massive oil spill, a government official said Friday.

The news comes as hearings before a federal investigative panel in Houston continue and oil giant BP prepares to permanently kill its undersea well.

Jane Lubchenco, head of the National Oceanic and Atmospheric Administration, told reporters that the government is reopening 4,281 square miles of federal waters off the coast of western Louisiana.

Oil sheen has not been seen there since July 29, and scientists found no oil or dispersants on samples of the area's shrimp and finfish.

Twenty percent of federal waters in the Gulf remain closed.

"We're sort of nibbling at the edges if you will, areas that have been free of oil for the longest time and were oiled the least," Lubchenco said.

The government has been seeking to assure consumers that Gulf seafood on the market is safe to eat.

The April 20 explosion that sank the Deepwater Horizon rig killed 11 workers and spewed 206 million gallons of oil from BP's undersea well. BP was operating the rig, which was owned by Transocean Ltd.

A temporary cap placed on the well in mid-July stopped oil from flowing into the sea. But that was considered a temporary solution.

The current plan is to pump mud and cement down through a relief well and seal the blown-out well from the bottom. Engineers are preparing to first remove the failed blowout preventer - a key piece of evidence - and replace it with another one.

Meanwhile, at the hearings before the joint U.S. Coast Guard-Bureau of Energy Management, Regulation and Enforcement investigative panel, a BP drilling engineer who was a key decision maker at the rig that blew up refused to testify Friday.

Mark Hafle exercised his constitutional right not to testify.

The panel's goal is to determine what caused the explosion on the Deepwater Horizon rig that led to the largest offshore oil spill in U.S. history. The panel also will make recommendations to prevent such a catastrophe in the future.