Washington, May 29 (DPA) President Barack Obama toured Louisiana’s southern coastline Friday to survey what has become the worst-ever US oil disaster, as energy company BP’s critical top-kill operation to cap the ruptured well in the Gulf of Mexico entered its third day.

Obama toured one of the state’s beaches, picking up tiny oil tar balls that had washed up along the shore, warning of the impact on wildlife and pledging never to ignore the local community’s plight.

‘You will not be abandoned. You will not be left behind,’ Obama told Gulf Coast residents, in a speech from a beach in Grand Isle, Louisiana. ‘We are on your side and we will see this through’.

The president’s visit – his second to the region since the April 20 Deepwater Horizon rig explosion – comes amid growing local anger and frustration over the government’s response to the disaster and BP’s inability to cap the oil well.

Obama said he had ordered the number of teams working at coastlines where oil has already washed up – as well as those that could be hit within 24 hours – to be tripled.

‘This is our highest priority and it deserves a response that is equal to the task,’ Obama said, acknowledging that the administration was now dealing with ‘the largest spill in American history’.

As many as 540,000 barrels of oil have spewed into the Gulf since April 20, more than the 257,000 barrels during the infamous 1989 Exxon Valdez spill in Alaska. The oil slick has now touched 240 km of US coastline, according to broadcaster CNN.

BP officials insisted the top-kill procedure was proceeding according to plan, though the company warned it would likely be another 48 hours before it was clear whether the complicated procedure was successful.

‘If it is successful it would obviously be welcome news,’ Obama said. ‘But our response will continue with its full force regardless of the outcome.’

As part of the operation, heavy mud was pumped into the well through much of Wednesday before engineers took a break to assess results. From Thursday night to Friday morning, BP forced down ‘bridging agents’ such as rubber balls and other solid objects – a variation of the so-called ‘junk shot’ technique.

The pumping of heavy mud was due to resume later Friday, said BP chief executive Tony Hayward. He noted that the operation had already at least temporarily stopped oil and gas coming out of the ruptured well, but pleaded for patience.

‘I know that’s frustrating for everyone. I am probably more frustrated than many,’ he told CNN. ‘I want to get this thing done.’

Hayward has also cautioned that top kill carries a risk of making the leak even larger, so engineers are proceeding with caution. A top kill has never been tried 1.6 kilometres under water.

The halting nature of the process was necessary to allow engineers to measure the pressure in the pipes, BP’s Chief Operating Officer Doug Suttles said Thursday.

‘You stop pumping. If the pressure begins to rise, you pump again. If it doesn’t rise, you have some sign of success,’ Suttles said.

Obama’s visit to the region comes as the administration faces growing criticism for its handling of the crisis and reliance on BP to cap the ruptured well. Obama was accompanied on his tour by Coast Guard Admiral Thad Allen, who is leading the federal government’s response to the disaster.

Obama acknowledged the ‘frustration and anger’ of the local community and insisted he carries full responsibility. But he has said only BP has the technological means to close the leak.

Should top-kill not work, BP is also drilling two relief wells that could permanently cut off the oil flow, but the drilling will not be complete until August.

Spain, the Netherlands and the European Union have offered equipment to help the United States clean up the oil, the European Commission said Friday.

The US has so far only accepted help from Mexico and Norway. Obama said Thursday that his administration would consider other offers as needed.