BP said it is forging ahead with efforts to contain the leak in the Gulf of Mexico as portions of heavy oil are being washed ashore near the Mississippi River, US.

The US government said yesterday that initial information provided by BP about the Gulf of Mexico oil spill had fallen short in its scope and effectiveness.

BP was also accused of seeking to conceal the extent of the damage and the amount of crude flowing unchecked from its ruptured well following the explosion of the Deepwater Horizon well.

BP and federal agencies initially estimated that the oil is leaking at 5,000bpd, which has been disputed by some scientists who claim the well is leaking about 70,000bpd.

BP said it will try to permanently plug the leaking well as early as 23 May by injecting heavy drilling fluid and cement near the top of the well, a technique known as top kill.

Meanwhile, the US Environmental Protection Agency has ordered BP to identify safer dispersants that can be used to fight the spill as fears grow about potential damage caused by the use of chemical treatments.

Canada has also tightened offshore drilling rules in response to the massive Gulf of Mexico oil spill, enforcing new requirements on Chevron‘s operations off Newfoundland.