THE White House was accused on Thursday of spinning a government scientific report into the amount of oil left in the Gulf of Mexico from the BP spill which had officials declaring that the vast majority of the oil had been removed.

As BP workers began pouring cement into the well as a first step to sealing it permanently, environmental groups and scientists — including those working with government agencies to calculate the scale and effects of the spill — said White House officials had painted far too optimistic a picture of a report by the National Oceanic and Atmospheric Agency (Noaa) into the fate of the oil.

“Recent reports seem to say that about 75 per cent of the oil is taken care of and that is just not true,” said John Kessler, of Texas A&M University, who led a National Science Foundation on-site study of the spill. “The fact is that 50 per cent to 75 per cent of the material that came out of the well is still in the water. It's just in a dissolved or dispersed form.”

With work beginning on the final phase of sealing the well, Thad Allen, the Obama administration's top official on the spill, told reporters there would be no new oil in the Gulf. But those assurances failed to satisfy scientists and environmental groups, who disputed the claim by Carol Browner, the White House energy and climate adviser, that “the vast majority of oil is gone”.

In Louisiana, state wildlife officials told CNN that tar balls and patches of oil were still washing up in the marshes and coastal areas of St Bernard, Plaquemines and Jefferson parishes.

Susan Shaw, a marine toxicologist and director of the Marine Environmental Research Institute, said the White House had been too quick to declare the oil was gone. “The blanket statement that the public understood is that most of the oil has disappeared. That is not true. About 50 per cent of it is still in the water,” she said.

Even the White House's own estimates still left a spill five times the size of that from the Exxon Valdez, she said, with long-term consequences that would be unknown for years to come.

Terry Hazen, the head of ecology at the Lawrence Berkeley national laboratory, who studied the spill for Noaa, said his teams could find no trace of oil on the surface or in the deep between 2km and 100km from the well site last week.

“Whatever was put into the environment, it is undetectable in the water column and the surface of water,” he said. But he added “That is not true though in the marshes or on some of the shorelines. We do know there is still oil out there.”

He also said there were potential weaknesses in the analysis because of Noaa's assumptions about the size of the spill. However, such nuances were overshadowed by the White House, which staged a high-profile event on Wednesday to announce that the well had stopped flowing, and that the consequences of the spill were not as catastrophic as once feared.

Francesca Griffo, senior scientist at the Union of Concerned Scientists, said the White House had stepped on more nuanced statements from Noaa scientists. “When these reports go through the spin machine they get distorted,” she said. “If you look closely at this report, it makes it very clear that this is not over.”

— The Guardian, London