A U.S. newspaper reported on Thursday that oil may be again leaking from BP's Macondo well in the Gulf of Mexico.

"Hundreds of small, circular patches of oily sheen dotted the surface within a mile of the wellhead," said The Mobile Press- Register, an Alabama newspaper.

Its reporters visited the site on Thursday and watched "blobs of oil rise to the surface and bloom into iridescent yellow patches," the newspaper said.

Most of the oil was located in a patch about 50 yards wide and a quarter of a mile long, and reporters found a "pronounced and pungent petroleum smell," the paper said.

While the source of the oil remained unclear, a chemical analysis by Louisiana State University scientists confirmed that the oil was a sweet Louisiana crude and could be from BP's Macondo well, said the newspaper.

However, the newspaper quoted experts as saying that the oil could be flowing from a natural seep on the seafloor near the BP wellhead.

Other possibilities include oil trapped within the wreckage of the well, or oil deposited on the bottom during the spill that is slowly working its way to the surface, the paper said.

The most troubling possibility, according to petroleum engineers, is that oil is leaking up through the seafloor surrounding the sealed Macondo well, the newspaper said.

Last week, in response to online reports suggesting the well had begun to leak again, BP issued a statement, stating: "none of this is true."

In an emailed statement, BP spokesman Justin Saia said Wednesday that the company stands by its previous statement, and that "neither BP nor the Coast Guard has seen any scientific evidence that oil is leaking from the Macondo well."

BP's Macondo well ruptured after an oil rig exploded and sank on April 20 last year, spewing up to 4.9 million barrels of oil into the Gulf of Mexico for nearly three months in the world's worst marine oil spill.