New Orleans: US officials said Tuesday they launched a criminal probe into the nation`s worst ever oil spill as BP voiced hopes of capping the six-week-old Gulf of Mexico leak soon.
"We will prosecute to the fullest extent of the law anyone who has violated the law," Attorney General Eric Holder told reporters in New Orleans. "We will not rest until justice is done."
As shares in the British energy giant plunged Tuesday, losing 13 percent and wiping off 12 billion pounds (17.6 billion dollars) off its market value, Holder said the criminal probe began "some weeks ago."
But he declined to elaborate on what kind of charges could be brought and against whom.
Holder was speaking after touring the region to witness the damage caused by the spill, triggered when an explosion ripped through the BP-operated Deepwater Horizon rig on April 20, sinking it two days later.
"What we saw this morning was oil for miles and miles. Oil that we know has already affected plant and animal life along the coast, and has impacted the lives and livelihoods of all too many in this region," he said.
US President Barack Obama also threatened to take legal action against those to blame, saying the government had an "obligation" to determine the cause of the "greatest environmental disaster of its kind in our history."
"If our laws were broken leading to this death and destruction, my solemn pledge is that we will bring those responsible to justice on behalf of the victims of this catastrophe and the people of the Gulf region," Obama vowed.
BP`s chief operating officer Doug Suttles said the company now hoped to cap the rig`s fractured pipe on Wednesday, thanks to a new operation launched Tuesday.
"If everything goes well, within the next 24 hours, we could have this contained," Suttles said in Louisiana.
But when asked later by Fox News about whether BP had broken any laws, Suttles replied: "I have no idea."
"We need to let the investigations run their course and they`ll find what they find and we`ll deal with that when they find it," he added.
At congressional hearings last month, BP traded blame for the disaster with rig owner Transocean and oil services group Halliburton, which was responsible for the well`s cement casing.
The latest operation -- dubbed a lower marine riser pipe -- would cut off the jagged edges of the leaking pipe and seal it with a tight cap. A tube would then siphon most of the oil to a ship on the surface.
In cutting the riser pipe, however, BP runs the risk of unleashing an even larger torrent of oil.
If it works, BP engineers plan to lower another dome to capture a second flow of oil through a valve known as the blowout preventer, BP`s managing director Bob Dudley said.
"By the end of the month, we are engineering a completely separate system that will make it more storm-proof with a free standing riser that would allow for quick disconnects if needed," he told CNN.
The official start of the hurricane season on Tuesday has worsened the outlook for residents in Louisiana and the neighboring states of Alabama and Mississippi, amid warnings the 2010 storm season will be more than active than usual, with up to 14 hurricanes.
Two deep relief wells BP is drilling into the seabed to plug the leak permanently will not be ready until August.
An estimated 12,000 to 19,00 barrels of crude have been belching daily into Gulf waters since the rig explosion.
Eleven workers were killed, and more than 20 million gallons of oil are estimated to have flooded into the Gulf.
US officials meanwhile expanded a Gulf of Mexico fishing ban, leaving 68 percent of waters open.
The boundaries were extended to the north and the south "to capture portions of the slick moving into waters off eastern Alabama and the western tip of the Florida panhandle, as well as some large patches of sheen moving onto the west Florida shelf and southward to Cuban waters," US officials said in a statement.
BP has tried -- and failed -- several times in the past six week to cap the leak, triggering mounting anger as oil washes up on the Gulf shores, threatening rare animal and plant life, as well as local livelihoods.
US officials said 29 dead dolphins and 227 sea turtles have been collected in the area so far -- above average for this time of year -- with at least one of each species showing visible signs of oil.