Washington, Aug 10 (DPA) US President Barack Obama said the long struggle to cap a gushing oil well in the Gulf of Mexico appeared "just about over," as oil company BP this week embarked on its final push to permanently plug the leak.

BP Plc said Monday that a relief well, which has been drilling its way towards the leaking reservoir for more than three months, could finish its work Sunday by injecting cement near the bottom of the ruptured well.

BP also said that cement pushed down from the top of the ruptured well - a separate effort begun last week known as the "static kill" - appeared to have hardened Sunday and already largely sealed off the leak.

The relief well's completion would permanently plug the worst oil spill in US history. About 4.9 million barrels of oil have spewed into the Gulf waters since April 20, washing up along the shores of four southern US states.

BP's costs related to the massive spill have hit $6.1 billion, the British company said Monday. The total includes the cost of the spill response, containment, relief-well drilling, and cementing up the damaged well.

Obama, speaking at the White House, said the static kill "appears to have succeeded," while "the final steps will be taken later in August when the relief well is completed."

"What is clear is that the battle to stop the oil from flowing into the Gulf is just about over," Obama said as he hosted the New Orleans Saints, an American football team that helped lift Gulf Coast spirits earlier this year by winning the Super Bowl.